sparse: use None as the sparse matcher value when disabled
This create a clear signal for when the feature is unused. We could also create
an `alwaysmatcher`, but using None is more explicit, so I went for it.
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
}