set the pipefail option, otherwise `foo | tee`'s status code will be 0 (success) even if foo failed

accordingly, must use bash instead of the default sh
make it possible to check package rev deps by writing [crandalf ???@user/repo] in the commit message, where ??? is the package name, and you can optionally specify the github repo

for example, let's see if it works with [crandalf highr@yihui/highr]