If a backup pass had been skipped (either because the transport was unavailable
or -- in a common case! -- because there was simply no work pending when the
periodic backup check fired), we were forgetting to reset the "backup currently
in progress" flag. Once we'd done that, the device would *NEVER* perform a
backup until it was rebooted, since it would forever think that there was one
currently in operation that must not be interfered with.
Change-Id: I0d6d7375dc6de99b599222a449934e70fe13ebb9
a253f16cf8