executor: repair debug mode

Don't print SYZFAIL messages during machine check.
Otherwise each of them is detected as a bug.

executor/executor_runner.h

@@ -443,7 +443,14 @@ class Proc
 		}
 		if (flag_debug) {
 			output_.resize(output_.size() + 1);
-			debug("proc %d: got output: %s\n", id_, output_.data() + debug_output_pos_);
+			const char* output = reinterpret_cast<char*>(output_.data()) + debug_output_pos_;
+			// During machine check we can execute some requests that legitimately fail.
+			// These requests have ReturnError flag, so that the failure is returned
+			// to the caller for analysis. Don't print SYZFAIL in these requests,
+			// otherwise it will be detected as a bug.
+			if (msg_ && IsSet(msg_->flags, rpc::RequestFlag::ReturnError) && strstr(output, "SYZFAIL"))
+				output = "REDACTED-CONTAINS-FAIL";
+			debug("proc %d: got output: %s\n", id_, output);
 			output_.resize(output_.size() - 1);
 			debug_output_pos_ = output_.size();
 		}