comparison tests/test-rhg.t @ 49149:006688e36e12 stable

rhg: use `Command::exec` instead of `Command::status`

`rhg` is supposed to be a transparent executable, using a subprocess defeats
that purpose. See inline comments for more details.

This also introduces the `which` crate to check if the fallback executable
actually exists to help debugging (plain `execve` doesn't give much
information).

The error code 253 is used to signify that the fallback is not found, but may
mean in the future that it is otherwise invalid if we start being more
specific.

Differential Revision: https://phab.mercurial-scm.org/D12578

49148:db3f8e5cc965

  $ rhg cat original --exclude="*.rs" --config rhg.fallback-executable=false
  [1]

  $ rhg cat original --exclude="*.rs" --config rhg.fallback-executable=hg-non-existent
  tried to fall back to a 'hg-non-existent' sub-process but got error $ENOENT$
  unsupported feature: error: Found argument '--exclude' which wasn't expected, or isn't valid in this context
  
  USAGE:
      rhg cat [OPTIONS] <FILE>...
  
  For more information try --help
  
  [252]

  $ rhg cat original --exclude="*.rs" --config rhg.fallback-executable=rhg
  Blocking recursive fallback. The 'rhg.fallback-executable = rhg' config points to `rhg` itself.
  unsupported feature: error: Found argument '--exclude' which wasn't expected, or isn't valid in this context
  

49149:006688e36e12

  $ rhg cat original --exclude="*.rs" --config rhg.fallback-executable=false
  [1]

  $ rhg cat original --exclude="*.rs" --config rhg.fallback-executable=hg-non-existent
  abort: invalid fallback 'hg-non-existent': cannot find binary path
  [253]

  $ rhg cat original --exclude="*.rs" --config rhg.fallback-executable=rhg
  Blocking recursive fallback. The 'rhg.fallback-executable = rhg' config points to `rhg` itself.
  unsupported feature: error: Found argument '--exclude' which wasn't expected, or isn't valid in this context