fix replacer's dtypes not respected for frame replace

Author: peterpanmj

pandas/core/internals/blocks.py

@@ -2833,6 +2833,8 @@ def _replace_coerce(
             if convert:
                 block = [b.convert(numeric=False, copy=True) for b in block]
             return block
+        if convert:
+            return [self.convert(numeric=False, copy=True)]
         return self
 
 

pandas/core/internals/managers.py

@@ -632,7 +632,7 @@ def comp(s, regex=False):
                         convert=convert,
                         regex=regex,
                     )
-                    if m.any():
+                    if m.any() or convert:
                         new_rb = _extend_blocks(result, new_rb)
                     else:
                         new_rb.append(b)

pandas/tests/frame/test_replace.py

@@ -1307,6 +1307,6 @@ def test_replace_method(self, to_replace, method, expected):
     def test_replace_replacer_dtype(self, replacer):
         # GH26632
         df = pd.DataFrame(["a"])
-        result = df.replace({"a": replacer})
+        result = df.replace({"a": replacer, "b": replacer})
         expected = pd.DataFrame([replacer])
         tm.assert_frame_equal(result, expected)