test-pattern: register the current the bundle2 capabilities string

The bundle capabilites are sent with every getbundle ssh connection. Every time
the protocol is updated, that string is altered. We get the part about bundle2
string replaced by $USUAL_BUNDLE2_CAPS$ so that we only have to change the
substitution whenever this happens.

tests/common-pattern.py

@@ -19,4 +19,17 b' substitutions = ['
      # (the replacement patterns)
      br'$USUAL_BUNDLE_CAPS$'
     ),
+    # bundle2 capabilities sent through ssh
+    (br'bundle2=HG20%0A'
+     br'changegroup%3D01%2C02%0A'
+     br'digests%3Dmd5%2Csha1%2Csha512%0A'
+     br'error%3Dabort%2Cunsupportedcontent%2Cpushraced%2Cpushkey%0A'
+     br'hgtagsfnodes%0A'
+     br'listkeys%0A'
+     br'phases%3Dheads%0A'
+     br'pushkey%0A'
+     br'remote-changegroup%3Dhttp%2Chttps',
+     # (replacement patterns)
+     br'$USUAL_BUNDLE2_CAPS$'
+    ),
 ]