Was getting segfaults with multiple services using
`x-develop` and `watch` at the same time. Turns out
the Moby path matcher lazily initializes the regex
pattern internally the first time it's used, so it's
not goroutine-safe.
Change here is to not use a global instance for the
ephemeral path matcher, but a per-watcher instance.
Additionally, the data race detector caught a couple
other issues that were easy enough to fix:
* Use the lock that's used elsewhere for convergence
before manipulating
* Eliminate concurrent map access when triggering
rebuilds
Signed-off-by: Milas Bowman <milas.bowman@docker.com>
7aaea283ca