To reproduce:
1. Open project attached by the user
2. Select game object "skybox_32bit" and in inspector set its texture shape to cube and max size to 8192
3. Click apply

Expected result: Applying is done correctly without any errors.
Actual result: Error : Overflow in memory allocator. UnityEditor.DockArea:OnGUI()

Reproduced on : 5.5.0f3, 5.6.0p1, 2017.1.0b2
On versions 5.4.x and earlier editor simply freezes.

Note: this only happens when importing large skybox. Importing a low-resolution skybox with same settings is done correctly.

Fixed in 2017.3.0a2