Handle case in the updater when master branch is not in local repo.

.ci/update_windows/update.py

@@ -62,6 +62,13 @@ except:
 
 print("checking out master branch")
 branch = repo.lookup_branch('master')
+if branch is None:
+    ref = repo.lookup_reference('refs/remotes/origin/master')
+    repo.checkout(ref)
+    branch = repo.lookup_branch('master')
+    if branch is None:
+        repo.create_branch('master', repo.get(ref.target))
+else:
     ref = repo.lookup_reference(branch.name)
     repo.checkout(ref)