chore(launch): improved git fetch time by specifying a refspec and …

…`depth=1` (#4459)

wandb/sdk/launch/utils.py

@@ -414,6 +414,20 @@ def apply_patch(patch_string: str, dst_dir: str) -> None:
         raise wandb.Error("Failed to apply diff.patch associated with run.")
 
 
+def _make_refspec_from_version(version: Optional[str]) -> List[str]:
+    """
+    Helper to create a refspec that checks for the existence of origin/main
+    and the version, if provided.
+    """
+    if version:
+        return [f"+{version}"]
+
+    return [
+        "+refs/heads/main*:refs/remotes/origin/main*",
+        "+refs/heads/master*:refs/remotes/origin/master*",
+    ]
+
+
 def _fetch_git_repo(dst_dir: str, uri: str, version: Optional[str]) -> str:
     """Clones the git repo at ``uri`` into ``dst_dir``.
 
@@ -428,7 +442,8 @@ def _fetch_git_repo(dst_dir: str, uri: str, version: Optional[str]) -> str:
     _logger.info("Fetching git repo")
     repo = git.Repo.init(dst_dir)
     origin = repo.create_remote("origin", uri)
-    origin.fetch()
+    refspec = _make_refspec_from_version(version)
+    origin.fetch(refspec=refspec, depth=1)
 
     if version is not None:
         try: