fix: name the dirty profiles profile_sync refuses

The refusal said the directory carried uncommitted changes without naming the profile, among about 375. It now lists the files git status reports, and says that --force writes over them.

scripts/profile_sync.py

@@ -4154,16 +4154,22 @@ def _refuse_dirty_tree(emulators_dir: str, names: list[str]) -> None:
         print(f"{e}. Pass --force to write anyway.", file=sys.stderr)
         raise SystemExit(1) from e
     if dirty:
+        # Another session may own the change, so the refusal names the files:
+        # --force writes over them.
+        one = len(dirty) == 1
         print(
-            f"{emulators_dir} carries uncommitted changes to the selected "
-            "profiles. Commit them first or pass --force.",
+            f"{', '.join(dirty)} {'has' if one else 'have'} uncommitted changes: "
+            f"commit {'it' if one else 'them'} or pass --force, which writes over "
+            f"{'it' if one else 'them'}.",
             file=sys.stderr,
         )
         raise SystemExit(1)
 
 
-def emulators_dir_is_dirty(emulators_dir: str, names: list[str] | None = None) -> bool:
-    """True when the profile directory carries uncommitted changes.
+def emulators_dir_is_dirty(emulators_dir: str, names: list[str] | None = None) -> list[str]:
+    """The files of the profile directory that carry uncommitted changes.
+
+    Paths read as the status prints them, from the repository root.
 
     ``names`` narrows the question to those profiles. Git is asked from
     inside the directory, so a profile tree that lives in another
@@ -4181,7 +4187,11 @@ def emulators_dir_is_dirty(emulators_dir: str, names: list[str] | None = None) -
         raise RuntimeError(
             f"cannot read the git status of {emulators_dir}: {result.stderr.strip()}"
         )
-    return bool(result.stdout.strip())
+    return sorted(
+        line[3:].split(" -> ")[-1].strip('"')
+        for line in result.stdout.splitlines()
+        if line.strip()
+    )
 
 
 def build_parser() -> argparse.ArgumentParser:

tests/test_profile_sync.py

@@ -5303,6 +5303,24 @@ class TestEmulatorsDirStatus(unittest.TestCase):
             self.assertTrue(profile_sync.emulators_dir_is_dirty(root, ["a"]))
             self.assertFalse(profile_sync.emulators_dir_is_dirty(root, ["b"]))
 
+    def test_the_refusal_names_the_changed_profile(self):
+        """One profile changed by another session among ~375 refused the
+        whole run without saying which."""
+        with tempfile.TemporaryDirectory() as root:
+            self._git("init", "-q", cwd=root)
+            for name in "abc":
+                Path(root, f"{name}.yml").write_text(f"emulator: {name}\n")
+            self._git("add", "a.yml", "b.yml", "c.yml", cwd=root)
+            self._git("-c", "user.name=t", "-c", "user.email=t@t", "commit", "-qm", "p", cwd=root)
+            Path(root, "b.yml").write_text("emulator: b2\n")
+            self.assertEqual(profile_sync.emulators_dir_is_dirty(root, ["a", "b", "c"]),
+                             ["b.yml"])
+            err = io.StringIO()
+            with contextlib.redirect_stderr(err), self.assertRaises(SystemExit):
+                profile_sync._refuse_dirty_tree(root, ["a", "b", "c"])
+        self.assertIn("b.yml has uncommitted changes", err.getvalue())
+        self.assertNotIn("a.yml", err.getvalue())
+
     def test_a_tree_outside_any_repository_is_not_clean(self):
         with tempfile.TemporaryDirectory() as root, mock.patch.dict(
             os.environ, {"GIT_CEILING_DIRECTORIES": str(Path(root).parent)}