Enfeeble failing subprocess doctests
Enfeeble failing subprocess doctests

These seem to have specific dates and require specific error messages
from basic POSIX utilities.  This patch is split out to explicitly
document the hacks applied to subprocess.

alex/wal-e,fdr/wal-e,ajmarks/wal-e,RichardKnop/wal-e,tenstartups/wal-e,heroku/wal-e,wal-e/wal-e,ArtemZ/wal-e,intoximeters/wal-e,x86Labs/wal-e,DataDog/wal-e,equa/wal-e,modulexcite/wal-e,nagual13/wal-e