tests/histedit-helpers.sh

obsolete: ensure that `getrevs` always return a set

When a set of revisions was empty, we were using an empty tuple. We now return an
empty frozenset to ensure the object could be used in an operation that requires a
set.

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"
}