The current version of linear (1.22) has incorrect constraints in its
cabal file (which has been corrected in a revision), so it is causing
this test to fail.
This commit just switches to another arbitrary package (cereal) for the
tests.
This commit does the following two things:
1. Changes the Haskell package used in the extraDependencies test from
releaser to conduit. The reason for this is that conduit is more
of a "core" package in Haskell, and it is more likely to always be
working. (If conduit is not compiling, then large chunks of Hackage
won't be working.)
2. Tighten up the GHCi test to actually use the package from
extraDependencies. It appears that GHCi can fail to import the
package from extraDependencies, and that doesn't cause GHCi to
return an error code, which means the test isn't actually testing
anything.
This new change makes it so that if the package from
extraDependencies is actually not included for some reason, then
this shellFor test should fail.
This allows packagePlatforms to pick up on the overall supported
platforms and schedule builds on Hydra for more than the evaluation
platform (usually x86_64-linux).
Contrary to database-id-class, linear is part of stackage and actively
maintained, so the test is less likely to fail due to version
constraint issues as it is currently.
