Use UTF-8 encoding when getting information about packed refs

Author: Klyahin Aleksey

git/refs/symbolic.py

@@ -87,7 +87,7 @@ def _iter_packed_refs(cls, repo):
         """Returns an iterator yielding pairs of sha1/path pairs (as bytes) for the corresponding refs.
         :note: The packed refs file will be kept open as long as we iterate"""
         try:
-            with open(cls._get_packed_refs_path(repo), 'rt') as fp:
+            with open(cls._get_packed_refs_path(repo), 'rt', encoding='UTF-8') as fp:
                 for line in fp:
                     line = line.strip()
                     if not line: