mq: fold the code paths to invoke editor into specific logic (qrefresh/qfold)
This factoring simplifies the succeeding patch to switch from
"ui.edit()" to "getcommiteditor()" for qrefresh/qfold.
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"
}