pw: fix inverted condition in shell_path error handling

usr.sbin/pw/pw_user.c

@@ -464,7 +464,7 @@ shell_path(char const * path, char *shells[], char *sh)
 						return shellpath;
 				}
 		}
-		if (sh == NULL)
+		if (sh != NULL)
 			errx(EX_OSFILE, "can't find shell `%s' in shell paths", sh);
 		errx(EX_CONFIG, "no default shell available or defined");
 		return NULL;

usr.sbin/pw/tests/pw_useradd_test.sh

@@ -402,7 +402,7 @@ user_add_bad_shell_body() {
 	populate_etc_skel
 
 	atf_check -s exit:0 ${PW} useradd foo -s sh
-	atf_check -s exit:78 -e ignore ${PW} useradd bar -s badshell
+	atf_check -s exit:72 -e inline:"pw: can't find shell \`badshell' in shell paths\n" ${PW} useradd bar -s badshell
 }
 
 atf_test_case user_add_already_exists