Diagnose bad times.  Thanks to Uriel.
 [rsc] --rw-rw-r-- M 840072 glenda sys 960 Feb 12 10:28 sys/src/cmd/touch.c
	/n/sourcesdump/2006/0212/plan9/sys/src/cmd/touch.c:14,19 - 
	/n/sourcesdump/2006/0213/plan9/sys/src/cmd/touch.c:14,20
	  void
	  main(int argc, char **argv)
	  {
	+ 	char *t, *s;
	  	int nocreate = 0;
	  	int status = 0;
	  
	/n/sourcesdump/2006/0212/plan9/sys/src/cmd/touch.c:20,26 - 
	/n/sourcesdump/2006/0213/plan9/sys/src/cmd/touch.c:21,30
	  	now = time(0);
	  	ARGBEGIN{
	  	case 't':
	- 		now = strtoul(EARGF(usage()), 0, 0);
	+ 		t = EARGF(usage());
	+ 		now = strtoul(t, &s, 0);
	+ 		if(s == t || *s != '\0')
	+ 			usage();
	  		break;
	  	case 'c':
	  		nocreate = 1;
	/n/sourcesdump/2006/0212/plan9/sys/src/cmd/touch.c:51,57 - 
	/n/sourcesdump/2006/0213/plan9/sys/src/cmd/touch.c:55,61
	  		fprint(2, "touch: %s: cannot wstat: %r\n", name);
	  		return 1;
	  	}
	- 	if ((fd = create(name, OREAD|OEXCL, 0666)) < 0) {
	+ 	if((fd = create(name, OREAD|OEXCL, 0666)) < 0){
	  		fprint(2, "touch: %s: cannot create: %r\n", name);
	  		return 1;
	  	}
 [rsc] --rw-rw-r-- M 840072 glenda sys 960 Feb 12 10:28 sys/src/cmd/touch.c