Fix branch creation for empty clone

jupyterlab_git/git.py

@@ -1323,7 +1323,7 @@ async def init(self, path):
             }
         return {"code": code, "actions": actions}
 
-    async def _empty_commit_for_init(self, path):
+    async def _empty_commit(self, path):
         cmd = ["git", "commit", "--allow-empty", "-m", '"First Commit"']
 
         code, _, error = await self.__execute(cmd, cwd=path)

jupyterlab_git/handlers.py

@@ -516,6 +516,15 @@ async def post(self, path: str = ""):
 
         if data["checkout_branch"]:
             if data["new_check"]:
+                #  Need to check if startpoint is valid
+                isStartPointValid = await self.git._get_branch_reference(
+                    data["startpoint"], local_path
+                )
+
+                #  If start point is not valid, we need to make an empty commit
+                if not isStartPointValid:
+                    await self.git._empty_commit(local_path)
+
                 body = await self.git.checkout_new_branch(
                     data["branchname"], data["startpoint"], local_path
                 )
@@ -716,7 +725,7 @@ async def post(self, path: str = ""):
         body = await self.git.init(self.url2localpath(path))
 
         if body["code"] == 0:
-            body = await self.git._empty_commit_for_init(self.url2localpath(path))
+            body = await self.git._empty_commit(self.url2localpath(path))
 
         if body["code"] != 0:
             self.set_status(500)