t7502-commit: Skip SIGTERM test on Windows

The implementation of exec on Windows is just a rough approximation of the
POSIX behavior. In particular, no real process "overlay" happens (a new
process is spawned instead and the parent process waits until the child
terminates). In particular, the process ID cannot be taken by the exec'd
process. But there is one test in t7502-commit.sh that depends on this.
We have to skip it on Windows.
Signed-off-by: NJohannes Sixt <j6t@kdbg.org>

t/t7502-commit.sh

@@ -234,7 +234,7 @@ cat >.git/FAKE_EDITOR <<EOF
 # kill -TERM command added below.
 EOF
 
-test_expect_success 'a SIGTERM should break locks' '
+test_expect_success EXECKEEPSPID 'a SIGTERM should break locks' '
 	echo >>negative &&
 	! "$SHELL_PATH" -c '\''
 	  echo kill -TERM $$ >> .git/FAKE_EDITOR

t/test-lib.sh

@@ -689,10 +689,12 @@ case $(uname -s) in
 	}
 	# no POSIX permissions
 	# backslashes in pathspec are converted to '/'
+	# exec does not inherit the PID
 	;;
 *)
 	test_set_prereq POSIXPERM
 	test_set_prereq BSLASHPSPEC
+	test_set_prereq EXECKEEPSPID
 	;;
 esac