libpq and psql not on same page about SIGPIPE

libpq compiled with --enable-thread-safety thinks it can set the SIGPIPE
signal handler. It thinks once is enough.

psql thinks it can arbitrarily flip the signal handler between SIG_IGN
and SIG_DFL. Ergo, after the first use of the pager for output, libpq's
SIGPIPE handling will be broken.

I submit that psql is unlikely to be the only program that does this,
and therefore that libpq must be considered broken, not psql.

regards, tom lane