S3 listing inconsistency can raise NPE in globber

FileSystem Globber does a listStatus(path) and then, if only one element is returned, getFileStatus(path).isDirectory() to see if it is a dir. The way getFileStatus() is wrapped, IOEs are downgraded to null

On S3, if the path has had entries deleted, the listing may include files which are no longer there, so the getFileStatus(path),isDirectory triggers an NPE

While its wrong to glob against S3 when its being inconsistent, we should at least fail gracefully here.

Proposed

1. log all IOEs raised in Globber.getFileStatus @ debug
2. catch FNFEs and downgrade to warn
3. continue

The alternative would be fail fast on FNFE, but that's more traumatic