tests/histedit-helpers.sh

transaction: fix __repr__() and make the default name bytes

This likely was always wrong on py3, since going back to aff5996f3043, these
were added as a r-strings.  Callers seem to always be supplying bytes, which
makes the `b'/'.join(...)` part OK, but then bytes can't be interpolated into
str with "%s", so it wouldn't have worked in either case.

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
}