user-visible env in GHCi sometimes wrong

Let M be the head module of a multi-module project.  
First compile M and all below it to objects:
   ghc --make M
Now start an interactive session with M:
   ghc --interactive M
ghci loads object code for M and all dependencies.  
Unfortunately the top-level env is then stuffed,
so that, for example
   1 + 2
yields
   <no file>:0: Variable not in scope: `+'
This doesn't happen if any of the modules have been 
compiled to bytecode, which inclines me to believe 
this is some difficulty with the renamer/typechecker.

This happens in the just-about-to-be-released 5.00.1 
sources, and probably the HEAD too.

Trac metadata

Trac field	Value
Version	5.0
Type	Bug
TypeOfFailure	OtherFailure
Priority	high
Resolution	ResolvedWon'tFix
Component	Compiler
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