revlog-compression: update the config to be a list format.revlog-compression is now a list of engine, the first supported one is to be used. Doing this have several benefits: 1) this is fully backward compatible, config using a single entry will be read as a single item list, not changing any behavior. 2) This open the way to use zstd by default without impacting platform were it is not available. This will be done in a later changesets. Using zstd provide a significant performance boost explained in : bb271ec2fbfb. However zstd is not available in some cases, A notable example is the `--pure` version of Mercurial which doesn't come with zstd support. Differential Revision: https://phab.mercurial-scm.org/D8148

remotefilelog: add 'changelog' arg to shallowcg1packer.generate (issue6269) This cause traceback on widening using narrow extension when remotefilelog is enabled. Differential Revision: https://phab.mercurial-scm.org/D8134

drawdag: abide by new createmarkers() API The `obsolete.createmarkers()` API was changed in 6335c0de80fa (obsolete: allow multiple predecessors in createmarkers, 2018-09-22) to prefer its precursors input to be a tuple instead of a single precursor. Let's fix `drawdag.py` to comply. Differential Revision: https://phab.mercurial-scm.org/D8149

lfutil: provide a hint if the largefiles/lfs cache path cannot be determined A coworker hit this error using an LFS repo in a stripped down environment, and didn't know how to resolve it. The final conditional is a bit fast and loose, but there is currently no 'posix' test in hghave, and it doesn't seem like it's worth adding for this since I think Windows is the only non-POSIX platform we run tests on. Differential Revision: https://phab.mercurial-scm.org/D8145

setup: exclude the __index__ module from itself when generating This module is generated on Windows to hold all of the extension names and the help summaries, so that they are discoverable inside the py2exe zipfile. The problem is this file is generated by dumping the disabled list, and that list comes from walking the filesystem. So once an install from source into a virtualenv created this module, then next build from source from that virtualenv would also see __index__.py in the filesystem, and include it. Clearly that's wrong because this isn't a real extension, so just filter it from the list when generating it. The Mercurial installer was unaffected by this, but the TortoiseHg package was. In the final package, `hg help -v extensions` and the panel of extensions both showed it. Differential Revision: https://phab.mercurial-scm.org/D8142

tests: stabilize test-amend.t on Windows If $TESTTMP isn't quoted in this context, it ends up like `C:Temphgtests.pikkoxchild1test-amend.t-obsstore-off`. Differential Revision: https://phab.mercurial-scm.org/D8144

tests: replace truncate(1) with inline python MSYS doesn't have truncate(1) installed by default, and FreeBSD looked unhappy with the arguments provided. Differential Revision: https://phab.mercurial-scm.org/D8147

tests: stabilize test-rename-merge2.t on Windows I have no idea why, but this shifted in b4057d001760. Differential Revision: https://phab.mercurial-scm.org/D8146

merge with stable

py3: fix EOL detection in commandserver.channeledinput This breaks TortoiseHg's email preview which sends b'\n' while readline request is issued and the loop never ends. Spotted by Matt Harbison.