[ issue 1290 ] fixed by checking for definitions by copatterns
[ issue 1290 ] test case
Merge remote-tracking branch 'upstream/master'

Conflicts:
	src/full/Agda/TypeChecking/Monad/Base.hs
	src/full/Agda/TypeChecking/Monad/Base/KillRange.hs
	src/full/Agda/TypeChecking/Monad/Signature.hs
	src/full/Agda/TypeChecking/Rules/Builtin/Coinduction.hs
	src/full/Agda/TypeChecking/Rules/Def.hs
	src/full/Agda/TypeChecking/Rules/Record.hs
	src/full/Agda/TypeChecking/Rules/Term.hs
	src/full/Agda/TypeChecking/Serialise.hs