Bizarre context resolution when parent context is block params

Sample fiddle: https://jsfiddle.net/wcoshgaL/4/

I have a helper that sets `value=omg` in context and `value=1` in block params. The template correctly renders the value from the block params.
Inside that, I call a second helper that sets `value=bar` in normal context.
I would expect `value` to be `bar` here since that is in the current context. However, it seems to pull the value out of the parent block param context instead....

Reproduce the context-resolution behavior using the linked JSFiddle, focusing on nested helpers, normal context, and block parameters. The issue is resolved when the inner helper's normal context value (`bar`) is selected instead of the parent block parameter value (`1`).

Written by the indexing model from the issue text.