tests: allow Google's internal builds of clang-format to be used These builds do not actually include any Google-specific formatting changes; the only reason they don't include the LLVM version number is due to a decision to elide the version number from *all* LLVM/clang projects. For most builds of clang-format, even "unofficial" ones, the LLVM version will be displayed; example: ``` clang-format version 14.0.0 (https://github.com/llvm/llvm-project.git 1830ec94ac022ae0b6d6876fc2251e6b91e5931e) ``` The Google-internal build looks like this: ``` clang-format version google3-trunk (1830ec94ac022ae0b6d6876fc2251e6b91e5931e) ``` Differential Revision: https://phab.mercurial-scm.org/D10538

#require execbit

  $ hg init
  $ echo a > a
  $ hg ci -Am'not executable'
  adding a

  $ chmod +x a
  $ hg ci -m'executable'
  $ hg id
  79abf14474dc tip

Make sure we notice the change of mode if the cached size == -1:

  $ hg rm a
  $ hg revert -r 0 a
  $ hg debugstate
  n   0         -1 unset               a
  $ hg status
  M a

  $ hg up 0
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg id
  d69afc33ff8a
  $ test -x a && echo executable -- bad || echo not executable -- good
  not executable -- good