Max authored Apr 22, 2024 and Marge Bot committed Jul 04, 2024

Fixes #10920, an issue where GHCi bails out when started alongside a
file named Prelude.hs or Prelude.lhs (even empty file suffices).

The in-source Note [GHCi and local Preludes] documents core reasoning.

Supplementary changes:

 * add debug traces for module lookups under -ddump-if-trace;
 * drop stale comment in GHC.Iface.Load;
 * reduce noise in -v3 traces from GHC.Utils.TmpFs;
 * new test, which also exercizes HomeModError.