completion: don't return with error from __gitcomp_file_direct()

completion: don't return with error from __gitcomp_file_direct()

In __gitcomp_file_direct() we tell Bash that it should handle our
possible completion words as filenames with the following piece of
cleverness:

  # use a hack to enable file mode in bash < 4
  compopt -o filenames +o nospace 2>/dev/null ||
  compgen -f /non-existing-dir/ > /dev/null

Unfortunately, this makes this function always return with error
when it is not invoked in real completion, but e.g. in tests of
't9902-completion.sh':

  - First the 'compopt' line errors out
    - either because in Bash v3.x there is no such command,
    - or because in Bash v4.x it complains about "not currently
      executing completion function",

  - then 'compgen' just silently returns with error because of the
    non-existing directory.

Since __gitcomp_file_direct() is now the last command executed in
__git_complete_index_file(), that function returns with error as well,
which prevents it from being invoked in tests directly as is, and
would require extra steps in test to hide its error code.

So let's make sure that __gitcomp_file_direct() doesn't return with
error, because in the tests coming in the following patch we do want
to exercise __git_complete_index_file() directly,

__gitcomp_file() contains the same construct, and thus it, too, always
returns with error.  Update that function accordingly as well.

While at it, also remove the space from between the redirection
operator and the filename in both functions.

Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>