test-glog.t: use printrevset extension to trace rewritten revsets
Using "hg log -G --print-revset" prints the revset generated by graphlog and
exits. This helps debugging and writing shorter tests.
It has been suggested to handle these tests with doctests. I think the
extension approach is better because:
- It tests the actual parameter set passed to graphlog.revset(), not what we
expect it to be. 'branch' and 'only-branch' are currently distinct options
but nothing prevents fancyopts to grow a notion of option aliasing one day,
where both options would be merged before reaching the command.
- It can be used as debug output interleaved with real log calls.
v2:
- Use a test extension instead of a global deprecated new option