Sink should respect a readable event on the destination stream

[benurb]

Hello 😄

by using grunt-contrib-imagemin I encountered a problem that I tracked down to vinyl-fs 2.3.0. If one attaches a listener to the readable event of the vinly-fs.dest stream, the new sink (introduced in df97b14 ) prevents it from firing. I attached a test to this PR that hopefully explains the problem better.

The problem is that the pipe() call in sink.js turns the stream into flowing mode. In this mode the stream does no longer emit a readable event (see Node docs).

This of course is a special case. Nevertheless the destination stream should not be turned into flowing mode if it's obvious that this was not intended. Imho that's the case if a developer adds a readable event listener, so I added a check for it.

Feedback is much appreciated! 😄

Ben

[phated]

This solution was suggested by @chrisdickinson. I'd like to get his feedback on your change.

[benurb]

Sure 👍
The main problem currently is that 2.3.0 introduces a breaking change in a minor version update. I guess not many people will notice this, but it's probably better if we can get this sorted out quickly.

[phated]

Yep, but a breaking change is intentional, this was a regression. Sorry about that.