bookmark: add a dedicated pretxnclose-bookmark hook
This new hook mirror the newly introduced 'txnclose-bookmark' but can abort the
transaction.
fixbundle() {
grep -v 'saving bundle' | grep -v 'saved backup' | \
grep -v added | grep -v adding | \
grep -v "unable to find 'e' for patching" | \
grep -v "e: No such file or directory" | \
cat
}