fix regex matching on revisions with deleted text or comments

RegexPair.matchmake crashed with a TypeError when a capture-group
pattern was applied to a revision whose text or comment was deleted or
suppressed (content is None). Guard both matching paths against None,
and make the no-capture-group path emit a None column for such
revisions instead of omitting the key entirely.

This carries forward the fix Kaylea Champion and Mako Hill made on the
mako_changes-20230429 branch (7e6cd5b), which predated the rewrite.

Adds a unit test for matchmake(None) and an end-to-end test against the
ikwiki dump, which contains revisions with deleted text and comments.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
(cherry picked from commit dbcae5c64e)

src/wikiq/__init__.py

@@ -463,7 +463,8 @@ class RegexPair(object):
         # if there are named capture groups in the regex
         if self.has_groups:
             # if there are matches of some sort in this revision content, fill the lists for each cap_group
-            if self.pattern.search(content) is not None:
+            # content can be None when the text or comment was deleted/suppressed
+            if content is not None and self.pattern.search(content) is not None:
                 m = self.pattern.finditer(content)
                 matchobjects = list(m)
 
@@ -491,12 +492,11 @@ class RegexPair(object):
         # there are no capture groups, we just search for all the matches of the regex
         else:
             # given that there are matches to be made
-            if type(content) in (str, bytes):
-                if self.pattern.search(content) is not None:
-                    m = self.pattern.findall(content)
-                    temp_dict[self.label] = ", ".join(m)
-                else:
-                    temp_dict[self.label] = None
+            if content is not None and self.pattern.search(content) is not None:
+                m = self.pattern.findall(content)
+                temp_dict[self.label] = ", ".join(m)
+            else:
+                temp_dict[self.label] = None
 
         return temp_dict