res_phreaknet: Don't emit warning on 0-second billed calls.

This particular branch may not serve much of a good purpose
anymore, but don't emit a warning simply because a number
answered and immediately hung up.

Author: InterLinked1

res/res_phreaknet.c

@@ -609,11 +609,14 @@ static int cdr_handler(struct ast_cdr *cdr)
 	}
 
 	if (!billsec && answer->tv_sec) {
-		int oldduration = duration;
+		int calcduration, oldduration = duration;
 		/* XXX May or may not be necessary anymore. Edge case where called party hangs up first... */
 		/* Manually fix the duration. Unfortunately, this sets billsec=duration, which is wrong. */
-		duration = duration ? duration : time(NULL) - cdr_channel->startsecs;
-		ast_log(LOG_WARNING, "Call was answered, but billsec is 0? Adjusting duration from %d to %d\n", oldduration, duration);
+		calcduration = time(NULL) - cdr_channel->startsecs;
+		duration = duration ? duration : calcduration;
+		if (duration != oldduration) {
+			ast_log(LOG_WARNING, "Call was answered, but billsec is 0? Adjusting duration from %d to %d\n", oldduration, duration);
+		}
 	}
 
 	ast_localtime(answer, &tm, NULL); /* Use the local time zone here, the server will use UTC. */