Stray main tag makes git pull origin main a silent no-op (tag shadows branch) #213

Summary

refs/tags/main (lightweight, → 0b3b528, #44) coexists with refs/heads/main. Git resolves an unqualified refspec by matching refs/tags/<name> before refs/heads/<name> (count_refspec_match() in remote.c), so the very common

git pull origin main

fetches the tag instead of the branch, then merges/rebases onto the tag's old commit. The command still exits 0, so the failure is silent: the checkout never updates.

Reproduction (against 0be7a76)

$ git fetch --dry-run origin main
 * tag               main       -> FETCH_HEAD        # expected: branch

$ git pull --rebase origin main
 * tag               main       -> FETCH_HEAD
Already up to date.                                   # exit 0, branch unchanged

A fully qualified refspec behaves correctly:

$ git fetch --dry-run origin refs/heads/main
 * branch            main       -> FETCH_HEAD

Impact

Every client that passes the short branch name to git pull — GUI clients such as UGit do exactly git pull --recurse-submodules origin main, and so do many scripts — silently stops receiving updates. Worse, with pull.rebase=true the local branch can be moved backwards to 0b3b528: rebasing onto an ancestor of HEAD is reported as "already up to date", so the commits above it are dropped from the branch.

We hit precisely this: local main was rewound one commit, and three consecutive pull attempts returned success without applying the ~105 upstream commits. git fetch without a refspec was equally stale, because the branch half of the pull never ran.

git pull with no arguments is unaffected (it resolves branch.<name>.merge rather than matching a remote ref by name), which makes the problem easy to misdiagnose.

Suggested fix

Delete the stray tag — every other tag in this repository follows v*, so main looks accidental:

git push origin :refs/tags/main

(or Releases → Tags → main → Delete in the GitHub UI).

Workaround for affected clients until then

git pull --rebase origin refs/heads/main

Reproduced with git 2.45.2.windows.1 on Windows.