System Information
Operating system: OSX
Graphics card: Radeon Pro 580 8192 MB

Blender Version
Broken:
Date 2019-03-08
Hash 5af85d904e5b
Branch: blender2.7

Working:
Date 2019-02-15
Hash faa255c0a4e4
Branch blender2.7

When using grease pencil the materials dropdown at the top of the screen isn't populating. It's empty and an odd shape. See screenshot.

Exact steps for others to reproduce the error
Start blender. File -> New File -> 2d Animation. Click the materials drop down at the top of the screen.