failure parsing depends field with package in user and global databases

[ecyrb]

When I had Cabal-1.12.0 in both my global and user databases, running virthualenv would fail.

Removing my user Cabal-1.12.0 fixed the problem, but was a dependency on the yesod I had built...

I don't know enough to say that having the same version of a package in my global and user databases isn't nonsensical, so maybe this is more an issue with me than with virthualenv -- and if so, then it might be beneficial (for clueless people like me :) to include a different error message.

Last bit of my virthualenv.log file (with the dependency strings) reformatted.

          ...
          Executing: ghc-pkg field Cabal-1.12.0 depends
            using inherited variable environment
            Process exited successfully
            Process output:
              depends: array-0.3.0.3-ea09841aaf8e340f109e7ae88f466cb2
                       base-4.4.1.0-1f81e4e7baf87af8ebbcf52b7bec2254
                       containers-0.4.1.0-f1a01354b46f586a2ae9c4625be9a212
                       directory-1.1.0.1-cbdf38734bd8fecb3519f4f9562ab1e4
                       filepath-1.2.0.1-16b7a7902f5c6a9398c10b6f4692a21f
                       old-time-1.0.0.7-7c5cbdbeec52c74fcdf7a52f1a3a00d2
                       pretty-1.1.0.0-ea03881a32f128dc4031082859a896d9
                       process-1.1.0.0-ded94950078eefc365bc43476bd795b0
                       unix-2.5.0.0-f4492dece9dbc86208534cb0c3e40076
              depends: array-0.3.0.3-ea09841aaf8e340f109e7ae88f466cb2
                       base-4.4.1.0-1f81e4e7baf87af8ebbcf52b7bec2254
                       containers-0.4.1.0-f1a01354b46f586a2ae9c4625be9a212
                       directory-1.1.0.1-cbdf38734bd8fecb3519f4f9562ab1e4
                       filepath-1.2.0.1-16b7a7902f5c6a9398c10b6f4692a21f
                       old-time-1.0.0.7-7c5cbdbeec52c74fcdf7a52f1a3a00d2
                       pretty-1.1.0.0-ea03881a32f128dc4031082859a896d9
                       process-1.1.0.0-ded94950078eefc365bc43476bd795b0
                       unix-2.5.0.0-f4492dece9dbc86208534cb0c3e40076
            Process error output:
        Found dependency strings:
           array-0.3.0.3-ea09841aaf8e340f109e7ae88f466cb2
           base-4.4.1.0-1f81e4e7baf87af8ebbcf52b7bec2254
           containers-0.4.1.0-f1a01354b46f586a2ae9c4625be9a212
           directory-1.1.0.1-cbdf38734bd8fecb3519f4f9562ab1e4
           filepath-1.2.0.1-16b7a7902f5c6a9398c10b6f4692a21f
           old-time-1.0.0.7-7c5cbdbeec52c74fcdf7a52f1a3a00d2
           pretty-1.1.0.0-ea03881a32f128dc4031082859a896d9
           process-1.1.0.0-ded94950078eefc365bc43476bd795b0
           unix-2.5.0.0-f4492dece9dbc86208534cb0c3e40076
           depends:
           array-0.3.0.3-ea09841aaf8e340f109e7ae88f466cb2
           base-4.4.1.0-1f81e4e7baf87af8ebbcf52b7bec2254
           containers-0.4.1.0-f1a01354b46f586a2ae9c4625be9a212
           directory-1.1.0.1-cbdf38734bd8fecb3519f4f9562ab1e4
           filepath-1.2.0.1-16b7a7902f5c6a9398c10b6f4692a21f
           old-time-1.0.0.7-7c5cbdbeec52c74fcdf7a52f1a3a00d2
           pretty-1.1.0.0-ea03881a32f128dc4031082859a896d9
           process-1.1.0.0-ded94950078eefc365bc43476bd795b0
           unix-2.5.0.0-f4492dece9dbc86208534cb0c3e40076

Couldn't parse package identifier depends: