tests/test-execute-bit.t

tests: allow age to go up to triple digits in test-shelve.t

We started to glob the age of shelved changes in 51934fc796c0, which says that
sometimes tests run slow and `hg shelve --list` says "2s" instead of "1s".
However in some instances, like [1], tests run so slow that the age goes up to
double digits ("13s" in that case). When that happens, `hg shelve --list`
output has less white spaces after the age, so let's glob the spaces too. We
probably won't ever need to handle triple digits there, but I went ahead and
left only 2 required white spaces in total.

[1]: https://buildd.debian.org/status/fetch.php?pkg=mercurial&arch=sparc64&ver=4.5-1&stamp=1518360804&raw=0

#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