templatefilters: document the json filter I don't know the exact reason why it was undocumented, but that would be because unicode is difficult for humans. Since the json filter can now get localstr back to UTF-8 as long as it is unprocessed (i.e. {desc|json} works, but {desc|firstline|json} doesn't), it seems good enough to advertise the json filter.

encoding: introduce tagging type for non-lossy non-ASCII string This fixes the weird behavior of toutf8b(), which would convert a local string back to UTF-8 *only if* it was lossy in the system encoding. Before b7b26e54e37a "encoding: avoid localstr when a string can be encoded losslessly (issue2763)", all local strings were wrapped by the localstr class. I think this would justify the round-trip behavior of toutf8b(). ASCII strings are special-cased, so the cost of wrapping with safelocalstr is negligible. (with mercurial repo) $ export HGRCPATH=/dev/null HGPLAIN= HGENCODING=latin-1 $ hg log --time --config experimental.evolution=all > /dev/null (original) time: real 11.340 secs (user 11.290+0.000 sys 0.060+0.000) time: real 11.390 secs (user 11.300+0.000 sys 0.080+0.000) time: real 11.430 secs (user 11.360+0.000 sys 0.070+0.000) (this patch) time: real 11.200 secs (user 11.100+0.000 sys 0.100+0.000) time: real 11.370 secs (user 11.300+0.000 sys 0.070+0.000) time: real 11.190 secs (user 11.130+0.000 sys 0.060+0.000)