add comment

Author: minggli

pandas/core/internals/blocks.py

@@ -801,6 +801,8 @@ def replace(self, to_replace, value, inplace=False, filter=None,
                                     copy=not inplace) for b in blocks]
             return blocks
         except (TypeError, ValueError):
+            # GH 22083, TypeError or ValueError occurred within error handling
+            # causes infinite loop. Cast and retry only if not objectblock.
             if self.dtype == 'object':
                 raise
             else: