su: silence a useless warning

When the requested shell matches the restricted shell, there is no reason
to issue a warning, since we will be doing precisely as requested.

Signed-off-by: Jouke Witteveen <j.witteveen@gmail.com>

login-utils/su-common.c

@@ -1149,6 +1149,7 @@ int su_main(int argc, char **argv, int mode)
 			shell = getenv("SHELL");
 
 		if (shell
+		    && strcmp(shell, su->pwd->pw_shell)
 		    && getuid() != 0
 		    && is_restricted_shell(su->pwd->pw_shell)) {
 			/* The user being su'd to has a nonstandard shell, and