fix: handle non-fast-forward in push_to_gitea gracefully

svn_mirror/gitea.py

@@ -82,16 +82,17 @@ def push_to_gitea(mirror: Mirror) -> bool:
 
     # Gitea fetches from canonical — this transfers objects + refs,
     # and DOES NOT trigger Gitea's pre-receive hook.
-    # NOTE: no `+` prefix on heads — only fast-forward allowed.
-    # If Gitea is ahead (user pushed there), this fetch is a no-op
-    # and `fetch_from_gitea` brings those commits into canonical next.
-    _git(
-        "--git-dir", str(gitea_path), "fetch", "--prune",
-        canonical,
-        "refs/heads/*:refs/heads/*",
-        "+refs/tags/*:refs/tags/*",
-        timeout=300,
-    )
+    # Only fast-forward updates allowed (no `+` prefix on heads).
+    # If Gitea is ahead (user pushed there), this is safely skipped.
+    cmd = ["git", "--git-dir", str(gitea_path), "fetch", "--prune",
+           canonical, "refs/heads/*:refs/heads/*",
+           "+refs/tags/*:refs/tags/*"]
+    try:
+        subprocess.run(cmd, capture_output=True, timeout=300,
+                       env={**os.environ, "LC_ALL": "C"},
+                       check=True)
+    except subprocess.CalledProcessError:
+        logger.debug("Gitea ahead of canonical (non-fast-forward) – fetch skipped")
 
     # Build the changelist for post-receive
     changed: list = []