System.FilePath.joinDrive problem

[Twan van Laarhoven]

Hello all,

The joinDrive function currently produces paths such as "C:File" when 
calling  "C:" </> "File". This is apparently handled in a special case:

 >              | otherwise = case a of
 >                                [a1,':'] | isLetter a1 -> a ++ b
 >                                _ -> a ++ [pathSeparator] ++ b

This seems wrong, as far as I know "C:File" is not a valid path. What is 
the reason for this special case?

In particular this problem results in cabal wanting to install packages 
to "E:Haskell" on my computer (unless I pass a --prefix flag).

Twan