Prior to this commit, if you wanted to use modifiers such as
`:exclusions` or `:classifier` for a dependency whose version you
were managing with `:managed-dependencies`, you would need to
explicitly pass a `nil` as the version string in the dependency
tuple. This commit adds some logic to coerce the vectors before
they are processed, so that if the version string is simply
omitted instead of being set to `nil`, the `nil` will be implicitly
inserted and things will continue to work as before.
This provides a slightly nicer and more intuitive UX for the
managed-dependencies feature.
This commit fixes#2205: when using managed dependencies in
a project, if the project itself was a non-SNAPSHOT version,
then when `lein install` and similar tasks were executed,
lein would check to make sure that none of the dependencies
were a SNAPSHOT version. lein was checking that directly against
the `:dependencies` vector, which would cause an NPE if a dependency
didn't specify a version number (because it was inheriting it from
the `:managed-dependencies` section).
This commit fixes the bug by calling the code that merges the
`:dependencies` and `:managed-dependencies` vectors together prior
to performing the SNAPSHOT check.
