Log Message:
Update to 0.12.6, from Soren Jacobsen in PR pkg/23730.

Changes since 0.12.5:
* Yet another unreadable file non-root regress bug fix.
* Added --list-increment-sizes option from the development branch.
  Previously this option was in the man page but was omitted in the code
  (thanks to Michael Schwendt for report).
* Regressing and restoring should now take less memory when processing
  large directories (noticed by Luke Mewburn and others).
* When regressing, remove mirror_metadata and similar increments first.
  This will hopefully help regressing a backup that failed because disk
  was full (reported by Erik Forsberg).
* Fixed rather important quoting problem: quoting directives like
  --windows-mode were simply ignored when rdiff-backup was running
  remotely!  I'm surprised no one noticed this.  Are none of you using
  --windows-mode or similar?
* Fixed handling of (lack of) daylight savings time.  Earlier bug would
  cause some files to be marked an hour later.  Thanks to Troels Arvin
  and Farkas Levente for bug report.