In Unity 5.6 the PhysicsManager2D is called CollisionListener2D (renamed in 2017.1)

How to reproduce:
1. Open user provided project
2. Enter play mode and wait (should crash in no more than 5 minutes)

Notes: Multiple different assertions are thrown during and just before the crash
Ex: 'contactManifold != NULL'; 'contactState != Collision2D::ContactInvalid'; 'colliderItr != m_Collisions.end()' and so on

Reproduced on: 5.6.0b6, 5.6.1p4, 2017.1.0b2, 2017.1.0b9, 2017.2.0a3
Not reproduced on: 5.6.0b5,
Not reproduced on: 2017.1.0b1 (Physics2D.Simulate and Physics2D.autoSimulation not present)
Regression introduced in: 5.6.0b6

========== OUTPUTING STACK TRACE ==================

0x00000001414F44A2 (Unity) dynamic_array<Collision2D::ContactManifold2D,8>::push_back
0x00000001414FD37D (Unity) PhysicsManager2D::PreSolve
0x000000014154DFA4 (Unity) b2Contact::Update
0x000000014154829E (Unity) b2ContactManager::Collide
0x000000014154D4CA (Unity) b2World::Step
0x0000000141511AD9 (Unity) PhysicsManager2D::Simulate
0x000000014151434E (Unity) PhysicsManager2D::FixedUpdate
0x00000001414F811C (Unity) `InitializePhysicsManager2D'::`2'::FixedUpdatePhysics2DFixedUpdateRegistrator::Forward
0x00000001405D3DDF (Unity) PlayerLoop
0x0000000140F8E95E (Unity) Application::UpdateScene
0x0000000140F910EF (Unity) Application::UpdateSceneIfNeeded
0x0000000140F9C04F (Unity) Application::TickTimer
0x00000001412A56FD (Unity) MainMessageLoop
0x00000001412A700E (Unity) WinMain
0x0000000141D87E60 (Unity) __tmainCRTStartup
0x00007FF8A0F52774 (KERNEL32) BaseThreadInitThunk
0x00007FF8A1070D61 (ntdll) RtlUserThreadStart

========== END OF STACKTRACE ===========

Fixed in: 2017.2.0b1
Backported to: 5.6.2p1, 2017.1.0f1