notmuch: Try harder to find GitHub patch URL

Make spacemacs//notmuch-open-github-patch try harder to find a patch for
the pull request.

CHANGELOG.develop

@@ -1743,6 +1743,8 @@ Other:
 - Use add-node-modules-path to automatically find local executables
   (thanks to jupl)
 - Disabled add-node-modules-path by default (thanks to Eivind Fonn)
+**** Notmuch
+- Try harder to find GitHub patch URL (thanks to Miciah Masters)
 **** OCaml
 - Allow initialization without requiring =opam= (thanks to Bernhard Schommer)
 - Fixed misused functions, =merlin= is a package not a layer

layers/+email/notmuch/funcs.el

@@ -91,7 +91,9 @@ messages in the current thread"
              (goto-char (point-min))
              (if (re-search-forward "https://github.com/.*\\.patch" nil t)
                  (match-string-no-properties 0)
-               (user-error "No patch found"))))))
+               (if (re-search-forward "https://github.com/[^/]+/[^/]+/pull/[0-9]+" nil t)
+                   (concat (match-string-no-properties 0) ".patch")
+                 (user-error "No patch found")))))))
     (with-current-buffer (get-buffer-create
                           (generate-new-buffer-name "*mail-github-patch*"))
       (condition-case exception