Warn on Tor versions with the 'tor-' prefix

Closes ticket 21096.

changes/ticket21096

@@ -0,0 +1,3 @@
+  o Minor features (linting):
+    - Enhance the changes file linter to warn on Tor versions that are
+      prefixed with 'tor-'. Closes ticket 21096.

scripts/maint/lintChanges.py

@@ -75,6 +75,8 @@ def lintfile(fname):
         elif not re.search('[fF]ixes ([a-z ]*)bug (\d+); bugfix on ',
                            contents):
             warn("bugfix incant is not semicoloned")
+        elif re.search('tor-([0-9]+)', contents):
+            warn("do not prefix versions with 'tor-'")
 
 
 if __name__ == '__main__':