GESPipeline fails to change state in case of errors in timeline

Submitted by Kyrylo V. Polezhaiev

Link to original bug (#753883)

Description

Created attachment 309729
empty project

If GESProject contains some specific errors or is empty (like in attachment), and on project "loaded" I say GESPipeline (which should play Timeline I extracted) to change state to PLAY, it only changes state to READY and then no action is performed asynchronously (thread pool relaxing).
gst_element_get_state, however waits infinitely (in case timeout is -1).

Attachment 309729, "empty project":
empty.xges