docs: prefer `hg diff --from/--to` over `-r` This patch includes updating away from the broken `hg diff -r 'date(...)'` (see not in previous patch). Differential Revision: https://phab.mercurial-scm.org/D9555

diff: add --from and --to flags as clearer alternative to -r -r I think it was mistake to let the `-r` flag accept two revisions in `hg diff` in 98633e60067c (Support for 0, 1, or 2 diff revs, 2005-05-07). The command clearly acts on two revisions and having a single flag to indicate which those are is unclear. It got worse when it started accepting revsets as input. This patch introduces `--from` and `--to` flags, each taking a single revision and each defaulting to the working copy. That means that `hg

commandserver: handle IOError related to flushing of streams After dispatch, without chg we have handling of flushing of streams and exception handling related to it. The exception handling part is important because there can be exceptions when flushing fout or ferr. One such case is in `test-basic.t` which was failing on python3+chg without this patch as this handling was missing from chg. Failure can be seen at https://foss.heptapod.net/octobus/mercurial-devel/-/jobs/128399 Honestly I am not sure which one of `chgserver.py` or `commandserver.py` the change should go in. Differential Revision: https://phab.mercurial-scm.org/D9517