Log the githash of the 10gen/jstestfuzz repository when the fuzzer's self-tests fail

(This came up when looking at a BF ticket with Sviatlana Zuiko.)

There is currently no information about the version of the 10gen/jstestfuzz repository we are running when it fails and the Build Baron ends up going off of the timestamp of when the Evergreen task ran. The following is the information that we log about the 10gen/jepsen repository.

branch=$(git symbolic-ref --short HEAD)

commit=$(git show -s --pretty=format:"%h - %an, %ar: %s")

echo "Git branch: $branch, commit: $commit"