Black puts standalone comments inside short exploded expressions *after* the expression

[RonnyPfannschmidt]

gotten:

         cwd=str(cwd),
-        env=_always_strings(dict(
-            os.environ,
-            # try to disable i18n
-            LC_ALL='C',
-            LANGUAGE='',
-            HGPLAIN='1',
-        ))
+        env=_always_strings(dict(os.environ, LC_ALL='C', LANGUAGE='', HGPLAIN='1')),
+        # try to disable i18n
     )

[ambv]

This is by design. Black changed 7 lines into 2 lines. Your code will be clearer if you put the standalone comment in front of the line.

I'll leave that open because currently we're putting the standalone comment after the line it's commenting which is contrary to the expectation. But the fix will be to put this comment in front of the reformatted line.

[carljm]

This is a duplicate of #22.