github submodule not working with local Jekyll server

[furnstahl]

When I try to run a local Jekyll server (with bundle exec jekyll serve --watch), it fails with the error message
Liquid Exception: Could not locate the included file 'submodules/bandframework/resources/sdkpolicies/bandsdk.md' in any of ["/Users/furnstah/Dropbox/git_rjf/BAND_project/bandframework.github.io/_pages"]. Ensure it exists in one of those directories and, if it is a symlink, does not point outside your site source. in _pages/software.md

If I explicitly add the file bandsdk.md locally in 'submodules/bandframework/resources/sdkpolicies/` then the local server works fine.

On github the link is [bandframework @ 49bb0cf](https://github.com/bandframework/bandframework/tree/49bb0cf0b1bf29d149f49af7ce64193d58726b3a)

In ./_pages/software.md the include_relative statement is:
{% include_relative submodules/bandframework/resources/sdkpolicies/bandsdk.md %}
which is what triggers the Liquid Exception above.

[danOSU]

Had the same issue.