Update cloning process

Author: KangarooKoala

upstream_utils/update_mpack.py

@@ -11,9 +11,37 @@
     git_am,
 )
 
+def get_repo_path(url, tempdir=None):
+    if tempdir is None:
+        tempdir = tempfile.gettempdir()
+    repo = os.path.basename(url)
+    dest = os.path.join(tempdir, repo)
+    dest = dest.removesuffix(".git")
+    return dest
+
+def open_repo(url, *, err_msg_if_absent):
+    os.chdir(tempfile.gettempdir())
+
+    dest = get_repo_path(url, os.getcwd())
+
+    print(f"INFO: Opening repository at {dest}")
+
+    if not os.path.exists(dest):
+        if err_msg_if_absent is None:
+            subprocess.run(["git", "clone", "--filter=tree:0", url])
+        else:
+            print(err_msg_if_absent, file=sys.stderr)
+            exit(1)
+    os.chdir(dest)
+
+def clone(url, tag):
+    open_repo(url, err_msg_if_absent=None)
+
+    subprocess.run(["git", "switch", "--detach", tag])
 
 def main():
-    upstream_root = clone_repo("https://github.com/ludocode/mpack", "v1.1.1")
+    clone("https://github.com/ludocode/mpack", "v1.1.1")
+    upstream_root = os.getcwd()
     wpilib_root = get_repo_root()
     wpiutil = os.path.join(wpilib_root, "wpiutil")