Case no. 725266. Sometimes a window with the texture slots appear before the crash, sometimes not.
Case 786598. I’ve verified that it happens only when a normal map is selected too. Even if we add normal map later by editing the texture.
Does it also crash when you add component to game object through add component in inspector? If so, try updating your system, I had a similar issue but got it fixed after system update.
It crash when adding a brush texture to the terrain Editor with a Normal map. My S.O. Ubuntu 14 LTS is always updated, I think that’s not the problem.