tests: add tests for typoed commands
This includes one test showing how disabling a command with e.g.
"extensions.rebase=!" results in the command not being
suggested. We'll fix that next.
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
}