GitLab

The variable XFAIL_TESTS is not used anymore since commit e90073f7

.

The description for the known failures are moved into the respective tests as
comments.

The following descriptions were dropped:

- surface-pattern-big: Didn't really explain the failure
- big-line: Test isn't failing any more
- self-intersecting: Only XFAIL on quartz, but description doesn't match this

The following tests don't have a xfail reference image and seem to fail just
because of not having a reference image at all (I kept their description for
now):

big-trap, long-lines, self-copy-overlap
Signed-off-by: Uli Schlachter <psychon@znc.in>