obsutil: move 'allprecursors' to the new modules
We have a new 'obsutil' module now. We move the high level utility there to
bring 'obsolete.py' back to a more reasonable size.
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
}