Steps to reproduce:
1. Open user-submitted project
2. Load Scene SampleScene
3. Pick object Switcher and click CycleCamera to see various rendering outputs:

3.1. LdrMsaa (active initially) has HDR disabled and MSAA enabled. No MSAA is seen
3.2. HdrMsaa has HDR enabled and MSAA enabled. MSAA is seen
3.3. LdrMdaaPp has HDR disabled, MSAA enabled and PostProcessingStackV2 attached (no volumes, effects or post-AA). MSAA works without HDR enabled in this case

Expected result: MSAA works regardless of HDR
Actual result: MSAA only works when HDR is enabled

Reproduced with: 2018.2.2f1, 2018.3.0a8
Not tested with pre-2018.2 due to backwards incompatibility

Additional user note: MSAA can be forced by changing the pipeline settings Render Scale. Cycle to the original LdrMsaa camera and observe that MSAA is not seen. Change the Render Scale in the LightweightAsset settings to something like 1.2 and notice that MSAA appears to work then