filemerge: remove unused arguments from `_merge()` Differential Revision: https://phab.mercurial-scm.org/D12014

simplemerge: take arguments as annotated context objects The labels we put in conflict markers are formatted so the part before the ':' (typically says things like "local") is padded so the ':' is aligned among the labels. That means that if you specify a long label for "base" but the conflict marker style is "merge" (i.e. 2-way), the other two will have unwanted padding. We often don't specify a label for the base, so we don't notice the problem (and it may very well be that it didn't exist before my D11972). I think the best fix is to pass the labels along with the context objects, so the low-level code that switches on the marker style to use (i.e. `simplemerge`) can do the formatting. This patch starts doing that by passing a fully-formatted label to `simplemerge`. A coming patch will move the formatting to `simplemerge`. Differential Revision: https://phab.mercurial-scm.org/D12013

filemerge: make `labels` a required arg for `_premerge()` We always pass labels, and it's always a non-empty list, so we can simplify a bit. Differential Revision: https://phab.mercurial-scm.org/D12012

filemerge: remove unnecessary check for empty string Looking at the statement just before, the string is clearly never empty (or otherwise falsy). Differential Revision: https://phab.mercurial-scm.org/D12011

tests: also test spaces in conflict marker labels Our fake merge tool printed the arguments using `$1` etc. without quotes, which means that the shell collapsed repeated spaces within the argument. That resulted in tests that did not pick up changes to the number of spaces. Differential Revision: https://phab.mercurial-scm.org/D12010

blackbox: change year in logs to ISO 8601 format AFAIK, year/month/day is not a format than anyone uses. It seems more sensible to me to use ISO 8601, as that's standard and unambiguously year-month-day. Compatibility-wise, I think it's acceptable to change the default format. It's most for human consumption. It's plausible that a few tools parse this format, but it has already changed in the past (for instance to add the current revision). Differential Revision: https://phab.mercurial-scm.org/D12006

blackbox: add milliseconds to blackbox logs by default The current second granularity is often not specific enough to determine whether an hg command is happening before or after some other event. Given that starting a process takes on the order of 1ms (well, for native processes. It's quite a bit more for python processes), microseconds seems like unnecessary noise. This also lines up behavior with the rust version, where we already switched to millisecond precision. Differential Revision: https://phab.mercurial-scm.org/D12005