upgrade: implement equality for 'improvement' object
Through the code, we use a mix of 'improvement' object and string. Having a
single type would be simpler. For this we need the object to be comparable.
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
}