call-with-port should not close port when dynamic extent exited

call-with-port is currently using dynamic-wind to close the port, but:

R6RS 8.2.6 says of call-with-port:
"If proc does not return, port is not closed automatically, except perhaps when it is possible to prove that port will never again be used for an input or output operation."

Since they use call-with-port, it looks like this would also make with-output-to-file, with-input-from-file, call-with-output-file, call-with-input-file not meet their similar requirement.

I'm doing some cool stuff with custom ports and generators/coroutines, but this is preventing it from working when using these with-port procedures.