@@ -51,6 +51,14 @@ Unreleased
     entry), file settings like ``data_file``, and any wrong-typed value in the
     ``[paths]`` section (`pull 2263`_).
 
+- Fix: ``coverage run`` refuses run-affecting command-line options like
+  ``--branch`` alongside ``--concurrency=multiprocessing``, since they can't
+  reach the subprocesses.  The check only recognized ``multiprocessing`` as the
+  entire option value, so ``--concurrency=multiprocessing,thread --branch``
+  slipped through and failed later with "Can't combine statement coverage data
+  with branch data".  Each named concurrency library is now considered (`pull
+  2270`_).
+
 - Fix: ``coverage annotate -d DIR`` raised an ``AssertionError`` if any
   measured file had an extension other than ``.py``, such as a ``.pyw`` file on
   Windows.  The original extension is now restored on the annotated copy (`pull
@@ -60,6 +68,7 @@ Unreleased
 .. _pull 2262: https://github.com/coveragepy/coveragepy/pull/2262
 .. _pull 2263: https://github.com/coveragepy/coveragepy/pull/2263
 .. _pull 2265: https://github.com/coveragepy/coveragepy/pull/2265
+.. _pull 2270: https://github.com/coveragepy/coveragepy/pull/2270
 .. _issue 2266: https://github.com/coveragepy/coveragepy/issues/2266
 .. _pull 2268: https://github.com/coveragepy/coveragepy/pull/2268
 
 
@@ -1017,7 +1017,7 @@ def do_run(self, options: optparse.Values, args: list[str]) -> int:
             show_help("Can't append to data files in parallel mode.")
             return ERR
 
-        if options.concurrency == "multiprocessing":
+        if "multiprocessing" in (options.concurrency or "").split(","):
             # Can't set other run-affecting command line options with
             # multiprocessing.
             for opt_name in ["branch", "include", "omit", "pylib", "source", "timid"]:
 
@@ -1181,6 +1181,18 @@ def test_multiprocessing_needs_config_file(self) -> None:
         assert msg in err
         assert "Remove --branch from the command line." in err
 
+    def test_multiprocessing_in_a_list_needs_config_file(self) -> None:
+        # The check has to consider each concurrency value, not just compare
+        # the whole option to "multiprocessing".
+        self.cmd_help(
+            "run --concurrency=multiprocessing,thread --branch foo.py",
+            help_msg=(
+                "Options affecting multiprocessing must only be specified "
+                + "in a configuration file.\n"
+                + "Remove --branch from the command line."
+            ),
+        )
+
     def test_run_debug(self) -> None:
         self.cmd_executes(
             "run --debug=opt1 foo.py",