There are some things which everyone of us stumble upon and found out that this
does not work. Sometimes, we hg developers know that these things does not works
because of experience. But this does not scale well when we have a new developer
or maybe a user who wants to see what does not work and is interested in fixing
that.
Checking in the tests about the things which don't work will help others to
reproduce these and also helps in fixing because of functionalities
./run-tests.py provides.
IIRC we had this thought in one of the previous sprints also to checkin some of
the known failures.
I am starting with checking in a basic test failure. But I plan to check in
more narrow related failures which we have found.
Unable to find easily what exactly broken with merges and narrow made me to
implement this idea so that we won't have similar problem in future.