Bash sources user configuration files under a number of conditions that
can cause issues with scripts when bash is used as the scriptlet shell.

Bash assumes it's being run under rsh/ssh if stdin is connected to a
socket and sources the user bashrc unless the environment variable
$SHLVL is >= 2.  Commit 6a4c6a02
switched from pipes to sockets when communicating with child processes
to work around SIGPIPE issues.  Normally $SHLVL would be inherited from
the shell running pacman, but operations involving scriptlets are
generally run with sudo which does not let the $SHLVL variable through
unless specifically configured to.

Similarly $BASH_ENV can cause bash to source user-specified configuration
files if set.

https://lists.gnu.org/archive/html/help-bash/2022-02/msg00082.html



Signed-off-by: Andrew Gregory <andrew.gregory.8@gmail.com>