tests: add guard check for suid support This adds a check for setuid and setgid support and guards a part of a test requiring this particular filesystem feature. Such feature is notably missing in the Nix/NixOS build sandbox and was causing the whole test to fail for the mercurial package. Differential Revision: https://phab.mercurial-scm.org/D11739

rhg: more efficient `HgPath::join` This commit makes `HgPath::join` slightly more efficient by avoiding one copy. It also avoids a particularly inefficient (quadratic) use of `HgPath::join` by using a new mutating function `HgPathBuf::push` instead. The name for `HgPathBuf::push` is chosen by analogy to `PathBuf::push`. Differential Revision: https://phab.mercurial-scm.org/D11721

relnotes: update 6.0 with the last changes for the release Differential Revision: https://phab.mercurial-scm.org/D11742

rhg: Fix `rhg status` file content comparison This is only used when a file’s metadata make its status ambiguous, which depends on timing of previous command executions. Differential Revision: https://phab.mercurial-scm.org/D11743

rhg: make it possible to opt out of `rhg cat` The reason an opt-out is needed is that there are still behavior differences between `rhg cat` and `hg cat`: - it does not interpret relative paths correctly - it does not interpret patterns correctly, e.g. 're:foobar$' would be interpreted as a verbatim filename - it does not implement the correct semantics of relpath matcher: if given a directory, `hg` concatenates all files in this directory, while `rhg` simply complains Differential Revision: https://phab.mercurial-scm.org/D11723

tests: run the whole hg-core/path_auditor test in a clean temp dir This makes the whole test happen in a clean temporary directory in `$TMPDIR/$random`, and simplifies the test a bit by eliminating unnecessarily dynamic path elements computations. Before this patch, the first part of the test was happening in `/tmp` itself. This allowed coincidentally named files placed in that directory to impact the outcome of the test. Additionally, this made the second part of the test fail on systems on which `$TMPDIR != /tmp`, because the inspected directory was different from the one in which the mock files were being written. This fully fixes the issue only partially solved in db2bc9e667a1. Differential Revision: https://phab.mercurial-scm.org/D11738