WARNING in hptSomeThingsBelowUs when using a source plugin

When using a source plugin with a stage2 compiler built with the devel2 flavour, there are a fair few warnings about hptSomeThingsBelowUs.

WARNING in hptSomeThingsBelowUs
  missing module CoercePlugin
  Probable cause: out-of-date interface files

I don't know if this just started happening or has been going on for a while. Is this warning cause for concern? Everything appears to work as expected despite this hiccup.

Trac metadata

Trac field	Value
Version	8.4.3
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
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