Re: [PATCH] pg_convert improvement

The patch is pretty straightforward, I just have one remark:

+       /* if no actual conversion happened, return the original string */
+       /* (we are checking pointers to strings instead of encodings because
+          `pg_do_encoding_conversion` above covers more cases than just
+          encoding equality) */

I think this could be done in one single comment and follow the preferred style
for multi-line comment, see [1].