t7528: fix failure under csh
Explicitly set sh mode for ssh-agent (ssh-agent -s) to prevent failure when user's login shell is csh-like. The failure is caused by propagation of the $SHELL value from the user's original shell despite the test and test harness explictly using sh, which makes ssh-agent emit initialization code for the wrong shell: > cd t > echo $SHELL /bin/tcsh > ./t7528-signed-commit-ssh.sh --verbose --debug [...] expecting success of 7528.2 'sign commits using literal public keys with ssh-agent': [...] ./t7528-signed-commit-ssh.sh: 1: eval: setenv: not found ./t7528-signed-commit-ssh.sh: 1: eval: setenv: not found [...] Signed-off-by: Kenneth Lorber <keni@his.com> Acked-by: brian m. carlson <sandals@crustytoothpaste.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>