When creating a passwd struct from a uid that is not in the passwd

database, set pw_gid to the user's gid instead of whatever the user
specified via the -g flag (or 0 if no -g).

plugins/sudoers/sudoers.c

@@ -950,7 +950,7 @@ set_runaspw(const char *user, bool quiet)
 	uid_t uid = sudo_strtoid(user + 1, NULL, NULL, &errstr);
 	if (errstr == NULL) {
 	    if ((pw = sudo_getpwuid(uid)) == NULL)
-		pw = sudo_fakepwnam(user, runas_gr ? runas_gr->gr_gid : 0);
+		pw = sudo_fakepwnam(user, user_gid);
 	}
     }
     if (pw == NULL) {