shell: fix leaking strings

There are two memory leaks in "shell.c". The first one in `run_shell()`
is trivial and fixed without further explanation. The second one in
`cmd_main()` happens because we overwrite the `prog` variable, which
contains an allocated string. In fact though, the memory pointed to by
that variable is still in use because we use `split_cmdline()`, which
may create pointers into the middle of that string. But as we do not
have a direct pointer to the head of the allocated string anymore, we
get a complaint by the leak checker.

Address this by not overwriting the `prog` pointer.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

shell.c

@@ -143,6 +143,7 @@ static void run_shell(void)
 		}
 
 		free(argv);
+		free(split_args);
 		free(rawargs);
 	} while (!done);
 }
@@ -216,9 +217,8 @@ int cmd_main(int argc, const char **argv)
 	count = split_cmdline(prog, &user_argv);
 	if (count >= 0) {
 		if (is_valid_cmd_name(user_argv[0])) {
-			prog = make_cmd(user_argv[0]);
-			user_argv[0] = prog;
-			execv(user_argv[0], (char *const *) user_argv);
+			char *cmd = make_cmd(user_argv[0]);
+			execv(cmd, (char *const *) user_argv);
 		}
 		free(prog);
 		free(user_argv);

t/t9400-git-cvsserver-server.sh

@@ -11,6 +11,7 @@ cvs CLI client via git-cvsserver server'
 GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
 export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 if ! test_have_prereq PERL; then

t/t9850-shell.sh

@@ -1,6 +1,8 @@
 #!/bin/sh
 
 test_description='git shell tests'
+
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success 'shell allows upload-pack' '