Created attachment 122319 [details]
backtrace

Steps:
1) Open Impress
2) Change to 'Slide Transitions' sidebar tab
3) Click 'Shape' group transition
4) Select 'Diamond' variant
5) Crash

Regression as this doesnt happen in 5.0.

Version: 5.0.4.2
Build ID: 2b9802c1994aa0b7dc6079e128979269cf95bc78
Locale: en-US (en_US.UTF-8)

Version: 5.2.0.0.alpha0+
Build ID: 513d5c5781ec14f8512432f31290a3d54c8d57df
CPU Threads: 2; OS Version: Linux 4.2; UI Render: default; 
TinderBox: Linux-rpm_deb-x86_64@70-TDF, Branch:master, Time: 2016-02-01_10:25:20
Locale: en-US (en_US.UTF-8)

$ glxinfo | grep OpenGL
OpenGL vendor string: nouveau
OpenGL renderer string: Gallium 0.4 on NVC1
OpenGL core profile version string: 4.1 (Core Profile) Mesa 11.2.0-devel (git-97eee90 2015-12-19 trusty-oibaf-ppa)
OpenGL core profile shading language version string: 4.10
OpenGL core profile context flags: (none)
OpenGL core profile profile mask: core profile
OpenGL core profile extensions:
OpenGL version string: 3.0 Mesa 11.2.0-devel (git-97eee90 2015-12-19 trusty-oibaf-ppa)
OpenGL shading language version string: 1.30
OpenGL context flags: (none)
OpenGL extensions:
OpenGL ES profile version string: OpenGL ES 3.0 Mesa 11.2.0-devel (git-97eee90 2015-12-19 trusty-oibaf-ppa)
OpenGL ES profile shading language version string: OpenGL ES GLSL ES 3.00
OpenGL ES profile extensions: