How to reproduce:
1. Create a new project
2. Go to Window -> Package Manager
3. Install and remove IncrementalCompiler

Expected result: the Incremental compiler is removed from the project
Actual result: The Package Manager window breaks with "Failed to resolve packages: EPERM operation not permitted"

Reproducible with: 2018.3.0a7, 2018.3.0b2
Not reproducible with: 2018.1.9f2, 2018.2.9f1, 2018.3.0a6
(@pedroa notes: NOT reproducible on 2018.3.0b1, but console exhibits errors)
(@pedro@ notes: Reproducible ONLY on Windows Editor).

Note: Entities package has the same issue, but a different regression version. Entities regression version is 2018.3.0a10