If an app is downloaded into our cache, but an app with the same hash is
already installed, don't bother notifying people about it.
Extracted the logic for finding the path to an apk on disk (given a
PackageInfo object) to also be used by AppUpdateStatusSerice.
Change logging so that if we discard a downloaded file we Log.i instead
of Utils.debugLog. This is so that when debugging a release build we can
see what is happening, because this specific problem was easier to debug
with release builds (rather than setting up a custom fdroid repo).
2a40e082e6