Reproduction steps:
1. Open the attached project "OutlineRepro.zip"
2. Open Scene "SampleScene"

Expected result: The cube in the scene has a green outline
Actual result: The whole cube is green, as ForwardLit pass is rendered first, then the custom one on top of it. The result is the outline pass is drawn on top of the actual object

Reproducible with: 7.0.1 - 7.6.0 (2019.4.24f1, 2020.1.0a26, 2020.2.0a11)
Not reproducible with: 8.0.1 - 12.0.0 (2020.1.17f1, 2020.2.7f1, 2020.3.4f1, 2021.1.4f1, 2021.2.0a14)

Notes:
- Couldn't test with HDRP, as the shader only works with URP