chgserver: backport py3 buffered I/O workarounds from procutil I've recently switched to new machine and I found chg's stdout is fully buffered. Even though chg server is a daemon process, it inherits the environment where the chg client originally forked the server. This means the server's stdout might have been wrapped by LineBufferedWrapper. That's why we need to do wrap/unwrap in both ways. The "if" condition in _restoreio() looks weird, but I'm not willing to clean things up because stdio behavior is fundamentally different between py2 and py3, and py2 support will be dropped anyway.

chg: reset errno prior to calling strtol() Otherwise we can't figure out if the last strtol() invocation failed or not.

chg: do not close dir fd while iterating It works so long as the dp is the last entry, but readdir(dp) would fail with EBADF. Let's not do that and close the dir fd explicitly.

chg: show debug message for each fd to be closed It helps debugging. The number of file descriptors should be small in most cases, so the console output wouldn't get bloated even with CHG_DEBUG=1.

chg: apply clang-format

errors: use InputError for some errors on `hg clone` Differential Revision: https://phab.mercurial-scm.org/D9329

errors: raise InputError when given non-existent paths etc Differential Revision: https://phab.mercurial-scm.org/D9328

errors: use InputError for errors about bad label names (tags etc) Differential Revision: https://phab.mercurial-scm.org/D9327

errors: use InputError for errors about bad paths Differential Revision: https://phab.mercurial-scm.org/D9326

destutil: raise more specific error when histedit.defaultrev is empty Differential Revision: https://phab.mercurial-scm.org/D9313

errors: raise more specific errors when default remote not configured Differential Revision: https://phab.mercurial-scm.org/D9312

errors: set detailed exit code to 30 for config errors This is per https://www.mercurial-scm.org/wiki/ErrorCategoriesPlan. Differential Revision: https://phab.mercurial-scm.org/D9311

errors: introduce StateError and use it from commands and cmdutil This very similar to an earlier patch (which was for `InputError`). In this patch, I also updated the transplant extension only because `test-transplant.t` would otherwise have needed a `#if continueflag`. Differential Revision: https://phab.mercurial-scm.org/D9310

errors: set detailed exit code to 100 for some remote errors This is per https://www.mercurial-scm.org/wiki/ErrorCategoriesPlan. Differential Revision: https://phab.mercurial-scm.org/D9309

errors: catch urllib errors specifically instead of using safehasattr() Before this patch, we would catch `IOError` and `OSError` and check if the instance had a `.code` member (indicates `HTTPError`) or a `.reason` member (indicates the more generic `URLError`). It seems to me that can simply catch those exception specifically instead, so that's what this code does. The existing code is from fbe8834923c5 (commands: report http exceptions nicely, 2005-06-17), so I suspect it's just that there was no `urllib2` (where `URLError` lives) back then. The old code mentioned `SSLError` in a comment. The new code does *not* try to catch that. The documentation for `ssl.SSLError` says that it has a `.reason` property, but `python -c 'import ssl; print(dir(ssl.SSLError("foo", Exception("bar"))))` doesn't mention that property on either Python 2 or Python 3 on my system. It also seems that `sslutil` is pretty careful about converting `ssl.SSLError` to `error.Abort`. It also is carefult to not assume that instances of the exception have a `.reason`. So I at least don't want to catch `ssl.SSLError` and handle it the same way as `URLError` because that would likely result in a crash. I also wonder if we don't need to handle it at all (because `sslutil` might handle all the cases). It's now early in the release cycle, so perhaps we can just see how it goes? Differential Revision: https://phab.mercurial-scm.org/D9318

errors: raise InputError in fancyopts If a value of wrong type is passed to a command line flag, that's cleary an InputError. Differential Revision: https://phab.mercurial-scm.org/D9308