Should detect unencypted backups even if --no-encryption omitted

[Olivier Berger]

When a backup was made with --no-encryption, subsequent calls to collection-status should auto-detect that it was not ecnrypted.

At the moment, issueing duplicity collection-status file:///whatever/ will report an error like :
IOError: [Errno 2] No such file or directory: '/whatever/duplicity-full-signatures.20100306T090815Z.sigtar.gpg'

It could detect that there's indeed a duplicity-full-signatures.20100306T090815Z.sigtar.gz instead of the .gpg file.

Hope this helps.

Best regards,