**System Information**
Ubuntu 14.04
MD Mobility Radeon HD 5000 Series
**Blender Version**
Broken: 2.74
**Short description of error**
After the object is deleted from the scene, if there were existing shape keys added to the object they are not removed from bpy.data.shape_keys collection. bpy.data.shape_keys['Key'].users is 0, however bpy.data.shape_keys['Key'].user points to
bpy.data.meshes['Cube'] (for ex.)
If all shape keys are removed from the object ( bpy.ops.object.shape_key_remove(all=True) ) before deleting it, the bpy.data.shape_keys collection is correctly cleared.
If you reopen the blend file the shape keys are properly removed.
**Exact steps for others to reproduce the error**
1. Add shape key to an object
2. Delete the shape key
3. Delete the object bpy.ops.object.delete()
4. bpy.data.shape_keys is empty
1. Add shape key to an object
2. Delete the mesh bpy.ops.object.delete()
3. bpy.data.shape_keys is not empty