In the "smudge with skip" test (i.e., the one that tests using
$GIT_LFS_SKIP_SMUDGE), we unset the variable in the environment, and
then check that it has indeed been removed.
We expect that the 'unset' program will work without issue, so let's
remove the check that ensures it so.
As an additional benefit (and the reason for this change in the first
place) we allow this test to continue to pass even when the latest
commit message mentions the word "GIT_LFS_SKIP_SMUDGE".
On some CI systems, the commit message from HEAD is placed in the
environment variable (e.g., APPVEYOR_REPO_COMMIT_MESSAGE_EXTENDED) and
hence causes this test to fail.
The printf(1) command, like it's C cousin, takes a format string as its
first argument. If a shell variable is passed as the first argument, it
will be interpreted as a format string; this can lead to surprising
behavior and can cause the test suite to fail if we accidentally insert
a format string character into the variable.
Modify all the places in the individual tests that we use a plain quoted
variable as the format string by running the following Ruby one-liner:
ruby -i -pe '$_.gsub!(/printf "\$/, %q(printf "%s" "$))' t/t-*.sh
Avoid modifying the test helpers, as there are places (such as calc_oid)
where we want to pass text containing escapes (such as "\n") and have
those be properly interpreted by printf(1).
