Stack templates can't declare extra-deps

[jsteiner]

We're trying to write a stack template that depends on packages that aren't in Stackage. Thus, we want to supply our own stack.yaml. Unfortunately, when using stack new with the template, it ignores our supplied stack.yaml and fails because the LTS doesn't have all the packages to match our requirements. I should note that we are using --force, so the stack.yaml is being written, but isn't being used for the initialize step.

Expected:

stack new uses the supplied stack.yaml, including extra-deps in the initialize step.

Actual:

stack new fails because the lts-5.11 does not have all the package to match our requirements.

Stack version

$ stack --version
Version 1.0.4 x86_64

[mgsloan]

stack new --solver should do the trick.

Also related to #1390

[snoyberg]

In newer Stack versions, if a stack.yaml is declared in the template then it is used.