tests/histedit-helpers.sh

tests: add tests for missing revlogs and revlog entries

The verify code is pretty poorly tested. It's easy to test missing
revlogs and missing revlog entries, so let's add tests for that.

Also add some more tests corrupting each type of revlog, so we test
the messages presented when reading a revision fails. The pure and
native implementations produce different error messages, so we have to
use (glob) in the tests.

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
}