Thanks to David Gasaway <dave@gasaway.org> for the patch.

dsync: break out of the while loop using 'break' instead of setting the failedcount number, otherwise this will trigger the warning later

trouble, causing all subsequent backups never to fire.

stop attempting to sync to current_backup, because if we do this then we do this then we don't take advantage of the hardlinking that is done later

Thanks to ulrich for the preliminary patch.

Closes Redmine#4049.

Run rsync command-line through a shell, so that single-quotes around excludes are interpreted (Closes: #677410)

When --exclude 'something' is passed directly to rsync without going through
a shell, rsync tries to match a file whose name contains single quotes, which is
definitely not what we want it to do: exclude arguments protected with single
quotes are meant to be passed to a shell.

The latter has a robust history wrt. dealing with excludes / glob / quoting
etc., let's use that instead of the shiny new sed-based way.

Hopefully this fixes http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=656968#31
and future incarnations of this class of bugs.