Issues with bundler during vendoring

[tesssie]

I am using bootboot to dual boot version of rails.

So bundle pack is installing only to vendor/cache-next only.

Bundle complete! 120 Gemfile dependencies, 623 gems now installed.
Use `bundle info [gemname]` to see where a bundled gem is installed.
Updating files in vendor/cache-next
# echo $DEPENDENCIES_NEXT
0

why is it not installing vendor/cache. This was my expected behavior. th