fix: handle empty svn commit output (no-op) gracefully

svn_mirror/git_to_svn.py

@@ -500,7 +500,28 @@ def _sync_git_to_svn_impl(mirror: Mirror) -> int:
                 input=message.encode("utf-8"),
                 wc=wc, timeout=120, auth_args=auth_args,
             )
+            try:
                 new_rev = _parse_commit_revision(result)
+            except GitToSVNError:
+                logger.warning(
+                    "svn commit no-op for %s on %s – recording HEAD",
+                    commit_hash[:8], svn_branch,
+                )
+                info = subprocess.run(
+                    ["svnversion", str(wc)],
+                    capture_output=True, text=True, timeout=30,
+                    env={**os.environ, "LC_ALL": "C"},
+                )
+                rev_text = (info.stdout or "").strip().split(":")[0]
+                try:
+                    new_rev = int(rev_text)
+                except (ValueError, TypeError):
+                    logger.warning(
+                        "Cannot determine current SVN revision for %s – "
+                        "skipping mapping",
+                        svn_branch,
+                    )
+                    continue
 
             # Restore the real author as svn:author revprop
             try: