PG Bug reporting form <noreply(at)postgresql(dot)org> writes:
> PGTYPEStimestamp_fmt_asc() returns the incorrect month when the format
> specifier %b is used.
Yeah, you're clearly right. Defining struct pg_tm's tm_mon differently
from the common understanding of struct tm's tm_mon may not have been
the greatest idea we ever had :-(. I dug through the uses of tm_mon in
the rest of ecpglib and didn't find any other similar mistakes, though.
Will fix, thanks for the report!
regards, tom lane