Revert "upgrade-zulip-from-git: Provide better error message on a bad refname."

This reverts commit c903128eb7.

scripts/lib/upgrade-zulip-from-git

@@ -148,34 +148,28 @@ try:
         )
 
     # Generate the deployment directory via git worktree from our local repository.
-    try_refs = [
-        f"refs/tags/{refname}",
-        f"refs/heads/{refname}" if args.local_ref else f"refs/remotes/origin/{refname}",
-    ]
-    commit_hash: str | None = None
-    fullref: str | None = None
-    for ref in try_refs:
-        result = subprocess.run(
-            ["git", "rev-parse", "--verify", ref],
+    try:
+        fullref = f"refs/tags/{refname}"
+        commit_hash = subprocess.check_output(
+            ["git", "rev-parse", "--verify", fullref],
             preexec_fn=su_to_zulip,
             text=True,
             stderr=subprocess.DEVNULL,
-            check=False,
-        )
-        if result.returncode == 0:
-            fullref = ref
-            commit_hash = result.stdout.strip()
-            break
-        elif result.returncode != 128:
-            result.check_returncode()
-    if not commit_hash or not fullref:
-        logging.error(
-            "Failed to resolve %s as a tag or %s branch name!",
-            refname,
-            "local" if args.local_ref else "remote",
-        )
-        sys.exit(1)
-
+        ).strip()
+    except subprocess.CalledProcessError as e:
+        if e.returncode == 128:
+            # Try in the origin namespace, or local heads if --local-ref
+            if args.local_ref:
+                fullref = f"refs/heads/{refname}"
+            else:
+                fullref = f"refs/remotes/origin/{refname}"
+            commit_hash = subprocess.check_output(
+                ["git", "rev-parse", "--verify", fullref],
+                preexec_fn=su_to_zulip,
+                text=True,
+                stderr=subprocess.DEVNULL,
+            ).strip()
+    refname = fullref
     subprocess.check_call(
         ["git", "worktree", "add", "--detach", deploy_path, refname],
         stdout=subprocess.DEVNULL,