[git-cl-try] update builders-map response handling

Remove code path.

Update new code path to expect one bucket, instead of a list.
Related:
https://chromium-review.googlesource.com/c/infra/infra/+/927792

TBR=tandrii@chromium.org
Bug: 800355
Change-Id: I60fbcf92dc242fc9b448760aaa5399320e257323
Reviewed-on: https://chromium-review.googlesource.com/928053
Commit-Queue: Nodir Turakulov <nodir@chromium.org>
Reviewed-by: Nodir Turakulov <nodir@chromium.org>
diff --git a/git_cl.py b/git_cl.py
index cf49aaf..c9ec13c 100755
--- a/git_cl.py
+++ b/git_cl.py
@@ -420,20 +420,9 @@
 
   bucket_map = {}
   for builder in builders:
-    builder_info = builders_map.get(builder, {})
-    if isinstance(builder_info, list):
-      # This is a list of masters, legacy mode.
-      # TODO(nodir): remove this code path.
-      buckets = map(_prefix_master, builder_info)
-    else:
-      buckets = builder_info.get('buckets') or []
-    if not buckets:
-      return None, ('No matching bucket for builder %s.' % builder)
-    if len(buckets) > 1:
-      return None, ('The builder name %s exists in multiple buckets %s.' %
-                    (builder, buckets))
-    bucket_map.setdefault(buckets[0], {})[builder] = []
-
+    bucket = builders_map.get(builder, {}).get('bucket')
+    if bucket:
+      bucket_map.setdefault(bucket, {})[builder] = []
   return bucket_map, None