D12127: Do not query properties when no interfaces are left

[Stefan Brüns]

bruns added a reviewer: broulik.

REPOSITORY
  R245 Solid

REVISION DETAIL
  https://phabricator.kde.org/D12127

To: bruns, #frameworks, broulik
Cc: kde-frameworks-devel, broulik, michaelh, ngraham, bruns