Use of plugins causes different SafeHaskellMode returned for the module

Use of plugins will mark safe inference as failed, even when the plugin does not modify anything. This can result in compile error when -XSafe is used. For example:

$ cat DefaultPlugin.hs
module DefaultPlugin (plugin) where
import GhcPlugins
plugin = defaultPlugin

$ cat B.hs
{-# OPTIONS_GHC -fplugin DefaultPlugin #-}
module B (answer) where
answer = 42

$ cat A.hs
{-# LANGUAGE Safe #-}
module A (main) where
import B
main = print answer

$ ...
A.hs:4:1: error:
    B: Can't be safely imported! The module itself isn't safe.

Trac metadata

Trac field	Value
Version	8.7
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
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