fix linting errors

Author: danielhrisca

pandas/core/frame.py

@@ -6484,8 +6484,6 @@ def combiner(x, y):
 
         if self.columns.equals(other.columns):
 
-            if self.empty and len(other) == other_idxlen:
-                return other.copy()
             if self.index.equals(other.index):
                 return self.copy()
             elif self.empty:
@@ -6504,7 +6502,11 @@ def combiner(x, y):
                     other_vals = other[col][diff_index]
                     new_dtype = find_common_type([this_vals.dtype, other_vals.dtype])
 
-                    series = Series([this_vals.values[0]] * len(new_index), dtype=new_dtype, index=new_index)
+                    series = Series(
+                        [this_vals.values[0]] * len(new_index),
+                        dtype=new_dtype,
+                        index=new_index
+                    )
 
                     series[self_index] = this_vals
                     series[diff_index] = other_vals