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

  $ rm -rf a
  $ hg init a
  $ cd a
  $ echo a > a
  $ hg ci -Am0
  adding a
  $ hg tag t1 # 1
  $ hg tag --remove t1 # 2

  $ hg co 1
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg tag -f -r0 t1
  $ hg tags
  tip                                3:a49829c4fc11
  t1                                 0:f7b1eb17ad24

  $ cd ..