further improved JiffyDOS badline avoidance

c64/kernal/iec/iec_jiffydos.s

@@ -192,15 +192,18 @@ jiffydos_wait_line:
 	beq jiffydos_wait_line_done        // screen is disabled, no need to watch for badlines
 
 	// Avoid 2 lines before the badline, otherwise VIC will ruin the synchronization
-!:
-	sec
 	lda VIC_RASTER
+	cmp #$2E
+	bcc jiffydos_wait_line_done        // we are safe, border - lot of time till badline
+!:
+	lda VIC_RASTER                     // carry is definitely set here!
 	sbc VIC_SCROLY
 	and #$07                           // we want 8 lowest bits
 	cmp #$06
 	bcs !-
 
 jiffydos_wait_line_done:
+
 	rts