Facility to mitigate double-breakage due to Data.Version.versionTag Deprecation

See https://groups.google.com/forum/#!topic/haskell-core-libraries/q9H-QlL_gnE

Trac metadata

Trac field	Value
Version
Type	Task
TypeOfFailure	OtherFailure
Priority	high
Resolution	Unresolved
Component	libraries/base
Test case
Differential revisions
BlockedBy
Related
Blocking
CC	ekmett, hvr
Operating system
Architecture

changed milestone to %7.10.1

changed weight to 7

added Ttask Trac import core libraries labels

see 5b8fa46c

closed

Trac metadata

Trac field	Value
Type	Task → FeatureRequest
Resolution	Unresolved → ResolvedFixed

added Tfeature request label and removed Ttask label

added Ttask label

added Phigh label