mq: use fallback patch name if no alpha-numeric in summary line (issue5025) Before this patch, "hg qimport -r REV" fails, if the summary line of description of REV doesn't contain any alpha-numeric bytes. In this case, all bytes in the summary line 'title' are dropped from 'namebase' by the code path below. namebase = re.sub('[\s\W_]+', '_', title.lower()).strip('_') 'makepatchname()' immediately returns this empty string as valid patch name, because patch name conflicting against empty string never exists. Then, "hg qimport -r REV" is aborted at creation of patch file with empty filename. This situation isn't so rare. For example, ordinary texts in Japanese often consist of non alpha-numeric bytes in UTF-8. This patch makes 'makepatchname()' use fallback patch name if the summary line of imported revision doesn't contain any alpha-numeric bytes.