A way to un-breakpoint a set_trace() line

This sounds kind of odd, let me explain.  I usually enter the debugger with an explicit call to set_trace().  Often, once I've hit that line a few times, I no longer need to stop there, but I don't want to restart the process.

Just as I can manually turn a regular line into a breakpoint with the 'b' command, I would love a way to turn a set_trace() line back into a regular, non-breaking line.  The set_trace function would still be called of course, but could examine the calling line to see if it had been marked as non-breaking, and continue.