Reproduction steps:

1. Open "networking_just_source.zip" project
2. On the "API Update Required" pop-up press "...Go Ahead!"
3. Update the scripts/assemblies Obsolete API's

Expected Result: The Obsolete scripts update
Actual Result: The Obsolete script update results in an Internal error/ API updating failed

Fixed in: 2018.1.0a1

Reproduced with: 2017.3.0b3, 2017.2.0f2, 2017.1.1p4, 5.6.3p4, 5.6.1p4, 5.6.1p2, 5.6.1p1, 5.6.1f1
Regression introduced in: 5.6.1f1
Did not reproduce on: 5.5.5f1

Note:
Internal error: Recursion detected while updating scripts (assembly index: 4 or assembly name: Assembly-CSharp.dll)
API updating failed.