Don't snip version conflicts

[mitchellwrosen]

It would be convenient for debugging a build failure if I could see all of the version information cabal knows about. Unfortunately it tends to do this:

(conflict: Cabal => containers==0.5.7.1/installed-0.5...)

What's after that 0.5...?? :)

[hvr]

The code in question is at

cabal/cabal-install/Distribution/Solver/Modular/Package.hs

Lines 57 to 67 in 28d7da0

	-- | String representation of an instance.
	showI :: I -> String
	showI (I v InRepo) = showVer v
	showI (I v (Inst uid)) = showVer v ++ "/installed" ++ shortId uid
	where
	-- A hack to extract the beginning of the package ABI hash
	shortId = snip (splitAt 4) (++ "...")
	. snip ((\ (x, y) -> (reverse x, y)) . break (=='-') . reverse) ('-':)
	. display
	snip p f xs = case p xs of
	(ys, zs) -> (if L.null zs then id else f) ys

[sebright]

See #6465 for another example of a truncated version.