Code review comment for lp://staging/~pauljnixon/loggerhead/context_in_diffs

Am I reading the new code correctly in that any pre-existing links (in
the previous format) will generate different results than they did
before this change? If so, that seems unfortunate.

How about making the number of lines of context an optional parameter
instead, like so:

    /diff/<rev_id>/<rev_id>?context=<context_lines>

This arrangement seems to better reflect the semantics of the situation
as well as both allowing old links continue to work and permit the
number of lines of context to be optional.