callPackage already calls makeOverridable, but that just
makes the function that evaluates to buildEnv overridable,
not buildEnv itself.
If no overridable version of buildEnv is used during construction,
users can't override e.g. `paths` at all
I supplied meta.outputsToInstall automatically in all
mkDerivation products, but some packages still don't use it.
The reported case: jekyll -> bundlerEnv -> buildEnv -> runCommand.
- Now `pkg.outputUnspecified = true` but this attribute is missing in
every output, so we can recognize whether the user chose or not.
If (s)he didn't choose, we put `pkg.bin or pkg.out or pkg` into
`systemPackages`.
- `outputsToLink` is replaced by `extraOutputsToLink`.
We add extra outputs *regardless* of whether the user chose anything.
It's mainly meant for outputs with docs and debug symbols.
- Note that as a result, some libraries will disappear from system path.
Originally wanted to include ignoreCollisions in cups-progs, but I think
it's better if we use ignoreCollisions only if there are _real_
collisions between files with different contents.
Of course, we also check whether the file permissions match, so you get
a collision if contents are the same but the permissions are different.
Signed-off-by: aszlig <aszlig@redmoonstudios.org>
