Patch taken from sagemath, without it some sage doctests fail just
because of the extraneous output.
From the patch description:
The default "pkgdatafilesbindir" is something like /var/cache/sympow
that will never be writable by unprivileged users (and cannot safely
be made that way). There is already a fallback to $HOME in the code
that works perfectly well, but by default sympow emits a warning when
it realizes that it can't write to e.g. /var/cache/sympow on the first
try. Since that's completely expected, we hide the warnings behind an
additional level of verbosity (VERBOSE >= 2 instead of VERBOSE >= 1).
0081690e2e