ArcRepository will crash on two wrong checksum replies

The first time the ArcRepository gets a checksum with unexpected results it
tries re-uploading the file and removes it from the list of pending files.
if (orgChecksum.equals(reportedChecksum)) {
[...]
} else {
if ([...])

else if (storeState == BitArchiveStoreState.UPLOAD_STARTED) {
ad.setState(arcfileName bitarchiveName
BitArchiveStoreState.UPLOAD_FAILED);
startUpload((RemoteFile) outstandingRemoteFiles.remove(arcfileName)
(ConnectedBitarchive) connectedBitarchives.get(bitarchiveName));
(note: startUpload sets state to UPLOAD_STARTED)
If the checksum is again wrong it will try reuploading the file but since it
has been removed this will result in a null-pointer-exception.
Note: If this bug is fixed and the file isn't removed this may lead to an
infinite loop continually switching state from STARTED to FAILED if the
checksum result from the job is always wrong.
NOTE: This bug is originally from Bugzilla bug_id=343.
This bug was previously assigned to JJA.