[File Watchers] Folder not unwatched when externally renamed

[jasonsanjose]

Discovered this issue in PR #6546 when fixing #6537.

1. In AppshellFileSystem._enqueueChange insert a conditional breakpoint to log change events: console.log(changedPath),false
2. Open any project
3. Add a directory externally in windows explorer, name it foo
4. In Explorer, rename the directory to bar
5. In Explorer, paste in any single file into bar
6. Observe log

C:/Program Files/Brackets/dev/samples/root/Getting Started/
C:/Program Files/Brackets/dev/samples/root/Getting Started/
C:/Program Files/Brackets/dev/samples/root/Getting Started/
C:/Program Files/Brackets/dev/samples/root/Getting Started/
C:/Program Files/Brackets/dev/samples/root/Getting Started/
C:/Program Files/Brackets/dev/samples/root/Getting Started/New folder/
C:/Program Files/Brackets/dev/samples/root/Getting Started/foo/
C:/Program Files/Brackets/dev/samples/root/Getting Started/bar/
C:/Program Files/Brackets/dev/samples/root/Getting Started/bar
C:/Program Files/Brackets/dev/samples/root/Getting Started/New folder/README.md
C:/Program Files/Brackets/dev/samples/root/Getting Started/foo/README.md
C:/Program Files/Brackets/dev/samples/root/Getting Started/foo/README.md
C:/Program Files/Brackets/dev/samples/root/Getting Started/bar/README.md
C:/Program Files/Brackets/dev/samples/root/Getting Started/bar/README.md
C:/Program Files/Brackets/dev/samples/root/Getting Started/New folder/README.md

This issue doesn't manifest in any user visible behavior immediately (it may if you try to recreate a folder reusing one of the older names), but it does leave file watchers in a bad state.

The main problem here is that invalid change events are fired with the old path name, e.g. C:/Program Files/Brackets/dev/samples/root/Getting Started/New folder/README.md. It seems that windows file watchers are smart enough that they stay with a folder even after it's renamed.

The issue is due to the fact that we don't unwatch a folder after a rename. I have a patch for that in a closed PR https://github.com/adobe/brackets/pull/6546/files#diff-0.

@peterflynn also noted that subfolders should also be unwatched and suggested an API change to FileWatcherDomain to add a method for unwatching all paths that start with a prefix.

[jasonsanjose]

Correction, I did find some user facing behavior. After following the above steps...

1. In Explorer, create another new folder, name it foo (remember that bar presently progressed from New folder->foo->bar)
2. Paste in any single file into foo
3. Observe file tree
4. The file pasted into foo does not appear

A new file watcher was never created for the new foo folder because the FileWatcherDomain hit it's watcher cache and does not add a new watcher for the new foo folder.

[peterflynn]

FBNC @jasonsanjose via #6565

[jasonsanjose]

Confirmed fixed. Closing.