Prevented query_utils.refs_expression() from looking for empty string in annotations map.

1 files changed, 1 insertions, 1 deletions

diff --git a/django/db/models/query_utils.py b/django/db/models/query_utils.py
index 0fedfac3e2..e3f6a730d5 100644
--- a/django/db/models/query_utils.py
+++ b/django/db/models/query_utils.py
@@ -258,7 +258,7 @@ def refs_expression(lookup_parts, annotations):
     Because the LOOKUP_SEP is contained in the default annotation names, check
     each prefix of the lookup_parts for a match.
     """
-    for n in range(len(lookup_parts) + 1):
+    for n in range(1, len(lookup_parts) + 1):
         level_n_lookup = LOOKUP_SEP.join(lookup_parts[0:n])
         if level_n_lookup in annotations and annotations[level_n_lookup]:
             return annotations[level_n_lookup], lookup_parts[n:]