Incorrect binding used to render generator templates

As of commit 5fa0457542b0ff541d0a80ff8c3561eec8e35959 (edge), Rails::Generator::Commands::Create appears to be passing the wrong binding to ERB.result.

1. Create a custom generator derived from either Rails::Generator::Base or Rails::Generator::NamedBase
2. Create a simple template and add the obligatory m.template() method call from manifest.
3. Create a test method in your custom generator that excepts a block parameter and yields to that block somewhere in its body.
4. Invoke that method from within the template and pass a block to it.

Note that although the method is callable, the block is never passed to the method on invocation. Any attempts to yield that block fail because &block is nil (whether implicitly or explicitly passed in). This is because the binding in which the template is rendered corresponds to the command, not the generator.

In my patch, I just provided for this case in Commands::Create.template() such that callers may pass in an optional :binding parameter. If passed in, template() uses the Generator binding and method invocations requiring blocks from within the template work fine.