merge default into stable for 5.1 release

rust-filepatterns: unescape comment character property There were multiple issues in the original implementation: a. the local variable "line" dropped soon after replace_slice() applied b. replace_slice() was noop since br"\#".len() != b"#" This patch uses bytes::Regex::replace_all() since it seems the simplest way to replace bytes of arbitrary length, and I don't think we have to avoid using Regexp here.

rust-filepatterns: use literal b'#' instead of cast

rust-filepatterns: fix type of warnings tuple to (bytes, bytes) Otherwise warn() in match.py would fail if the warning contains non-ASCII character. We might want to add a thin ByteString wrapper around Vec<u8> to implement ToPyObject<ObjectType = PyBytes>, but I'm not sure.

hgignore: add escape syntax test for glob patterns The last example, [\#], is what the rust implementation fails to parse. The other escapes can be removed by regexp engine or _globre().

hgignore: add a few more weird patterns to test case

hgignore: update \-escape test to reflect actual behavior "\\<char>" is not an escape character but "\\" + <char>.

py3: add a b'' prefix in tests/test-convert-identity.t Differential Revision: https://phab.mercurial-scm.org/D6662

lookup: don't use "00changelog.i@None" when lookup of prefix fails We were shadowing the "node" variable, so we always passed None to the LookupError instead of the node we meant to pass. (This showed up in py3 tests since py3 doesn't like to format None using "%s".) Differential Revision: https://phab.mercurial-scm.org/D6661

py3: fix test-setdiscovery.t on Python 3 by conditionalizing two lines I'm not clear why this behaves very slightly differently on Python 3, but I'm also not concerned about it. Differential Revision: https://phab.mercurial-scm.org/D6658