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* Fix ``logjam-upload`` so that it keeps track of the files it's
uploaded. This considerably reduces the number of S3 GET requests
made to list objects in the target bucket.
* Fix ``logjam-compress`` so that if the compressed path for log
already exists, it won't replace the file. Instead, it compresses
the log file into a different path, which includes a prefix
denoting that this was the result of a pre-existing compressed
logfile.
* Add optional exception reporting from sentry if $SENTRY_DSN is
provided in the environment and raven (the Sentry client) is
installed.