I generated a config locally with:
$ ./mach python testing/mozharness/scripts/release/update-verify-config-creator.py --product firefox --stage-product firefox --app-name browser --branch-prefix mozilla --platform mac --to-version 139.0b3 --to-app-version 139.0 --to-build-number 1 --to-buildid 20250502090704 --to-revision 31e4fdec367808459b8a8f969ef041ca7e5eb8e0 --last-linux-bz2-version 134.99.0 --output-file update-verify.cfg --repo-path releases/mozilla-beta --partial-version 138.0b9 --partial-version 139.0b1 --partial-version 139.0b2 --updater-platform linux-x86_64 --channel beta-localtest --archive-prefix https://archive.mozilla.org/pub --aus-server https://aus5.mozilla.org --include-version '^(\d+\.\d+(b\d+)?)$' --mar-channel-id-override '^\d+\.\d+(\.\d+)?$$,firefox-mozilla-beta,firefox-mozilla-release' --last-watershed 138.0(this is a command pulled from a production log, with last-watershed adjusted to minimize work)
This gave me a plausible looking config:
release="139.0" product="Firefox" platform="Darwin_x86_64-gcc3-u-i386-x86_64" build_id="20250430182947" locales="ach af an ar ast az be bg bn br bs ca ca-valencia cak cs cy da de dsb el en-CA en-GB en-US eo es-AR es-CL es-ES es-MX et eu fa ff fi fr fur fy-NL ga-IE gd gl gn gu-IN he hi-IN hr hsb hu hy-AM ia id is it ja-JP-mac ka kab kk km kn ko lij lt lv mk mr ms my nb-NO ne-NP nl nn-NO oc pa-IN pl pt-BR pt-PT rm ro ru sat sc sco si sk skr sl son sq sr sv-SE szl ta te tg th tl tr trs uk ur uz vi xh zh-CN zh-TW" channel="beta-localtest" patch_types="complete partial" from="/firefox/releases/139.0b2/mac/%locale%/Firefox 139.0b2.dmg" aus_server="https://aus5.mozilla.org" ftp_server_from="https://archive.mozilla.org/pub" ftp_server_to="https://archive.mozilla.org/pub" to="/firefox/candidates/139.0b3-candidates/build1/mac/%locale%/Firefox 139.0b3.dmg" to_build_id="20250502090704" to_display_version="139.0 Beta 3" to_app_version="139.0" updater_package="/firefox/releases/139.0b2/linux-x86_64/%locale%/firefox-139.0b2.tar.xz" release="139.0" product="Firefox" platform="Darwin_x86_64-gcc3-u-i386-x86_64" build_id="20250428155722" locales="ach af an ar ast az be bg bn br bs ca ca-valencia cak cs cy da de dsb el en-CA en-GB en-US eo es-AR es-CL es-ES es-MX et eu fa ff fi fr fur fy-NL ga-IE gd gl gn gu-IN he hi-IN hr hsb hu hy-AM ia id is it ja-JP-mac ka kab kk km kn ko lij lt lv mk mr ms my nb-NO ne-NP nl nn-NO oc pa-IN pl pt-BR pt-PT rm ro ru sat sc sco si sk skr sl son sq sr sv-SE szl ta te tg th tl tr trs uk ur uz vi xh zh-CN zh-TW" channel="beta-localtest" patch_types="complete partial" from="/firefox/releases/139.0b1/mac/%locale%/Firefox 139.0b1.dmg" ftp_server_from="https://archive.mozilla.org/pub" ftp_server_to="https://archive.mozilla.org/pub" updater_package="/firefox/releases/139.0b1/linux-x86_64/%locale%/firefox-139.0b1.tar.xz" release="138.0" product="Firefox" platform="Darwin_x86_64-gcc3-u-i386-x86_64" build_id="20250421163656" locales="de en-US ru" channel="beta-localtest" patch_types="complete" from="/firefox/releases/138.0/mac/%locale%/Firefox 138.0.dmg" ftp_server_from="https://archive.mozilla.org/pub" ftp_server_to="https://archive.mozilla.org/pub" mar_channel_IDs="firefox-mozilla-beta,firefox-mozilla-release" updater_package="/firefox/releases/138.0/linux-x86_64/%locale%/firefox-138.0.tar.xz" release="138.0" product="Firefox" platform="Darwin_x86_64-gcc3-u-i386-x86_64" build_id="20250421163656" locales="ach af an ar ast az be bg bn br bs ca ca-valencia cak cs cy da dsb el en-CA en-GB eo es-AR es-CL es-ES es-MX et eu fa ff fi fr fur fy-NL ga-IE gd gl gn gu-IN he hi-IN hr hsb hu hy-AM ia id is it ja-JP-mac ka kab kk km kn ko lij lt lv mk mr ms my nb-NO ne-NP nl nn-NO oc pa-IN pl pt-BR pt-PT rm ro sat sc sco si sk skr sl son sq sr sv-SE szl ta te tg th tl tr trs uk ur uz vi xh zh-CN zh-TW" channel="beta-localtest" patch_types="complete"
And plausible looking log output:
14:35:37 INFO - Retrieving buildid from info file: https://archive.mozilla.org/pub/firefox/candidates/138.0-candidates/build1/macosx64_info.txt - attempt: #1
14:35:37 INFO - retry: Calling _urlopen with args: (), kwargs: {'url': 'https://hg.mozilla.org/releases/mozilla-beta/raw-file/FIREFOX_139_0b2_RELEASE/browser/locales/shipped-locales'}, attempt #1
14:35:38 INFO - retry: attempt #1 caught HTTPError exception: HTTP Error 404: Not Found
14:35:38 INFO - retry: Failed, sleeping 5 seconds before retrying
14:35:43 INFO - retry: Calling _urlopen with args: (), kwargs: {'url': 'https://hg.mozilla.org/releases/mozilla-beta/raw-file/FIREFOX_139_0b2_RELEASE/browser/locales/shipped-locales'}, attempt #2
14:35:44 INFO - retry: attempt #2 caught HTTPError exception: HTTP Error 404: Not Found
14:35:44 INFO - retry: Failed, sleeping 5 seconds before retrying
14:35:49 INFO - retry: Calling _urlopen with args: (), kwargs: {'url': 'https://hg.mozilla.org/releases/mozilla-beta/raw-file/FIREFOX_139_0b2_RELEASE/browser/locales/shipped-locales'}, attempt #3
14:35:50 INFO - retry: attempt #3 caught HTTPError exception: HTTP Error 404: Not Found
14:35:50 INFO - retry: Failed, sleeping 5 seconds before retrying
14:35:55 INFO - retry: Calling _urlopen with args: (), kwargs: {'url': 'https://hg.mozilla.org/releases/mozilla-beta/raw-file/FIREFOX_139_0b2_RELEASE/browser/locales/shipped-locales'}, attempt #4
14:35:56 INFO - retry: attempt #4 caught HTTPError exception: HTTP Error 404: Not Found
14:35:56 INFO - retry: Failed, sleeping 5 seconds before retrying
14:36:01 INFO - retry: Calling _urlopen with args: (), kwargs: {'url': 'https://hg.mozilla.org/releases/mozilla-beta/raw-file/FIREFOX_139_0b2_RELEASE/browser/locales/shipped-locales'}, attempt #5
14:36:02 INFO - retry: attempt #5 caught HTTPError exception: HTTP Error 404: Not Found
14:36:02 INFO - couldn't fetch file from hg; trying github
14:36:02 INFO - retry: Calling _urlopen with args: (), kwargs: {'url': 'https://raw.githubusercontent.com/mozilla-firefox/firefox/refs/tags/FIREFOX_139_0b2_RELEASE/browser/locales/shipped-locales'}, attempt #1
14:36:02 INFO - retry: Calling _urlopen with args: (), kwargs: {'url': 'https://hg.mozilla.org/releases/mozilla-beta/raw-file/FIREFOX_139_0b2_RELEASE/browser/config/version.txt'}, attempt #1
14:36:03 INFO - retry: attempt #1 caught HTTPError exception: HTTP Error 404: Not Found
14:36:03 INFO - retry: Failed, sleeping 5 seconds before retrying
14:36:08 INFO - retry: Calling _urlopen with args: (), kwargs: {'url': 'https://hg.mozilla.org/releases/mozilla-beta/raw-file/FIREFOX_139_0b2_RELEASE/browser/config/version.txt'}, attempt #2
14:36:09 INFO - retry: attempt #2 caught HTTPError exception: HTTP Error 404: Not Found
14:36:09 INFO - retry: Failed, sleeping 5 seconds before retrying
14:36:14 INFO - retry: Calling _urlopen with args: (), kwargs: {'url': 'https://hg.mozilla.org/releases/mozilla-beta/raw-file/FIREFOX_139_0b2_RELEASE/browser/config/version.txt'}, attempt #3
14:36:15 INFO - retry: attempt #3 caught HTTPError exception: HTTP Error 404: Not Found
14:36:15 INFO - retry: Failed, sleeping 5 seconds before retrying
14:36:20 INFO - retry: Calling _urlopen with args: (), kwargs: {'url': 'https://hg.mozilla.org/releases/mozilla-beta/raw-file/FIREFOX_139_0b2_RELEASE/browser/config/version.txt'}, attempt #4
14:36:20 INFO - retry: attempt #4 caught HTTPError exception: HTTP Error 404: Not Found
14:36:20 INFO - retry: Failed, sleeping 5 seconds before retrying
14:36:25 INFO - retry: Calling _urlopen with args: (), kwargs: {'url': 'https://hg.mozilla.org/releases/mozilla-beta/raw-file/FIREFOX_139_0b2_RELEASE/browser/config/version.txt'}, attempt #5
14:36:26 INFO - retry: attempt #5 caught HTTPError exception: HTTP Error 404: Not Found
14:36:26 INFO - couldn't fetch file from hg; trying github
14:36:26 INFO - retry: Calling _urlopen with args: (), kwargs: {'url': 'https://raw.githubusercontent.com/mozilla-firefox/firefox/refs/tags/FIREFOX_139_0b2_RELEASE/browser/config/version.txt'}, attempt #1
14:36:26 INFO - Adding 139.0b2 to update paths
14:36:26 INFO - retry: Calling _urlopen with args: (), kwargs: {'url': 'https://hg.mozilla.org/releases/mozilla-beta/raw-file/FIREFOX_139_0b1_RELEASE/browser/locales/shipped-locales'}, attempt #1
14:36:30 INFO - retry: Calling _urlopen with args: (), kwargs: {'url': 'https://hg.mozilla.org/releases/mozilla-beta/raw-file/FIREFOX_139_0b1_RELEASE/browser/config/version.txt'}, attempt #1
14:36:33 INFO - Adding 139.0b1 to update paths
14:36:33 INFO - retry: Calling _urlopen with args: (), kwargs: {'url': 'https://hg.mozilla.org/releases/mozilla-release/raw-file/FIREFOX_138_0_RELEASE/browser/locales/shipped-locales'}, attempt #1
14:36:35 INFO - retry: Calling _urlopen with args: (), kwargs: {'url': 'https://hg.mozilla.org/releases/mozilla-release/raw-file/FIREFOX_138_0_RELEASE/browser/config/version.txt'}, attempt #1
14:36:37 INFO - Adding 138.0 to update paths
14:36:37 INFO - [mozharness: 2025-05-02 14:36:37.322703Z] Finished gather-info step (success)