pycompat: adding Linux detection and fixing Mac Python 3 recommends detecting OSs with the prefix of the platform, but we were comparing the full string for macOS. We also didn't have Linux detection, which is convenient for extensions to use (rather than have some OSs detected by hg and some by the extension). Reference: https://docs.python.org/3/library/sys.html#sys.platform Differential Revision: https://phab.mercurial-scm.org/D5227

remotefilelog: fix various minor py3 problems # skip-blame b prefixes and pycompat.long, nothing remotely interesting Differential Revision: https://phab.mercurial-scm.org/D5223

remotefilelog: rip out a missed mention of lz4 Differential Revision: https://phab.mercurial-scm.org/D5222

ui: wrap whole _write() block with timeblockedsection I think the cost of color labeling is negligible compared to the I/O syscalls. Let's simply wrap the whole write() function so that we can eliminate _write() and _write_err() in later changeset.

ui: indent _writenobuf() to prepare moving bits from _write() functions

ui: simply concatenate messages before applying color labels This should be cheaper in space than applying labels for each message.

ui: simplify interface of low-level write() functions _write() and _write_err() will be replaced with fout.write() and ferr.write() respectively. This is the first step.

ui: factor out function that writes data to fout/ferr with labeling I'm thinking of adding an option to send status messages to stderr (or a dedicated command-server channel) so that structured output (e.g. JSON) would never be interleaved with non-formatter output. A unified write() interface helps to do that.

ui: consolidate places where _progclear() is called The progress bar has to be cleared when we start writing some data to the output stream. Let's make it always triggered immediately before switching by _colormode, so that we can easily factor out helper functions.

templater: compute revset lazily This speeds up e.g. "{ifcontains(rev, revset('::.'), ...)}" in common cases where 'rev' is near the working parent. The templater API is ugly, but it helps here. 'f' can be either a generator or a function returning a generator.