Replace `test -f` and `test ! -f` with `test_path_is_file` and
`test_path_is_missing` for better debuggability.
While `test -f` ensures that the file exists and is a regular file,
`test_path_is_file` provides clearer error messages on failure.
On the other hand, `test ! -f` checks either the absence of a regular
file or the presence of any other filesystem object, but looking at
them in the test individually, all of them should've said `test ! -e`,
i.e. "there shouldn't be anything at given path on filesystem."
Replace these cases with `test_path_is_missing` for better
debuggability.
Helped-by: karthik nayak <karthik.188@gmail.com> Helped-by: Junio C Hamano <gitster@pobox.com> Signed-off-by: Meet Soni <meetsoni3017@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>