EWS incorrectly parse bug id for bugs which reference another bug id in title. This cause EWS to skip such patches. e.g.: https://bugs.webkit.org/show_bug.cgi?id=190919 has title: "Revert r237347 registered custom properties... https://bugs.webkit.org/show_bug.cgi?id=190039" This bug wasn't processed by EWS. Corresponding logs on one of the bot (bindings-ews) are: 2018-10-25 16:16:09,302 - Fetching: https://bugs.webkit.org/attachment.cgi?id=353122&action=edit 2018-10-25 16:16:10,218 - Fetching: https://bugs.webkit.org/show_bug.cgi?id=190039&ctype=xml&excludefield=attachmentdata 2018-10-25 16:16:11,139 - Error in fetching attachment 353122 [details], bug_id: 190039 2018-10-25 16:16:11,139 - Skip 2018-10-25 16:16:12,216 - Releasing work item 353122 from bindings-ews Logs indicate that after fetching patch 353122, EWS tried to fetch incorrect bug 190039 (instead of 190919). Another old example: https://bugs.webkit.org/show_bug.cgi?id=170094 with title: "Revert instrumentation from https://bugs.webkit.org/show_bug.cgi?id=170086 when no longer needed." <rdar://problem/31894087>
The issue is in _parse_bug_id_from_attachment_page() method in: https://trac.webkit.org/browser/webkit/trunk/Tools/Scripts/webkitpy/common/net/bugzilla/bugzilla.py#L514
Also, once EWS has incorrectly processed the patch, changing the bug title (to remove bug id), and re-clicking on "Submit for EWS analysis" doesn't seems to help. It's probably because EWS doesn't have the feature to re-try a patch.
Workaround: change the bug title (to remove reference of other bug) and re-upload the patch.
EWS has been re-implemented from scratch. It uses REST API instead of parsing the webpage through BeautifulSoup. REST API is much more reliable and this issue shouldn't happen in new EWS.