logcmdutil: rewrite jsonchangeset printer to be backed by jsonformatter This is a bit slower than the original implementation, but I don't think that would actually matter. It's still faster than full templating. $ hg log -Tjson -r0:5000 --time > /dev/null (orig) time: real 1.550 secs (user 1.500+0.000 sys 0.040+0.000) (new) time: real 1.810 secs (user 1.740+0.000 sys 0.070+0.000) cf. $ hg log -Tdefault -r0:5000 --time > /dev/null time: real 4.980 secs (user 4.850+0.000 sys 0.130+0.000) $ hg log -r0:5000 --time > /dev/null time: real 2.340 secs (user 2.220+0.000 sys 0.100+0.000) $ hg log -r0:5000 -q --time > /dev/null time: real 0.750 secs (user 0.670+0.000 sys 0.070+0.000) The test output changes because keys are sorted alphabetically.