[tracker] (3 commits) Non-fast-forward update to branch sam/website

[Sam Thursfield <sthursfield src gnome org>]

The branch 'sam/website' was changed in a way that was not a fast-forward update.
NOTE: This may cause problems for people pulling from the branch. For more information,
please see:

 https://wiki.gnome.org/Git/Help/NonFastForward

Commits removed from the branch:

  10dc9b7... Add an initial website for Tracker, built using mkdocs

Commits added to the branch:

  bde247a... libtracker-data: Fix potential NULL pointer dereference (*)
  ef0027c... docs: Fix missing tracker-ontologies.xml reference (*)
  0a9a540... Add an initial website for Tracker, built using mkdocs

(*) This commit already existed in another branch; no separate mail sent