BUG: fix hash_tuples with length 1 tuples

Author: TomAugspurger

pandas/core/util/hashing.py

@@ -146,7 +146,7 @@ def hash_tuples(vals, encoding='utf8', hash_key=None):
     from pandas import Categorical, MultiIndex
 
     if not isinstance(vals, ABCMultiIndex):
-        vals = MultiIndex.from_tuples(vals)
+        vals = MultiIndex.from_tuples(vals, squeeze=False)
 
     # create a list-of-Categoricals
     vals = [Categorical(vals.labels[level],