Following the instructions in the Jekyll documention http://jekyllrb.com/docs/collections/, I created a collection in my jekyll blog for developer related posts
collections:
developer:
output: true
On a jekyll page, I try to output a list of the posts like this
<ul class="posts">
{% for post in site.developer %}
<li>
<span class="post-date">{{ post.date | date: "%b %-d, %Y" }}</span>
<a class="post-link" href="{{ post.url | prepend: site.baseurl }}">{{ post.title }}</a>
<p>{{ post.excerpt }}</p>
</li>
{% endfor %}
</ul>
This works on my local machine. I can view one post from this collection at
http://localhost:4000/developer/2014-07-07-blah-blah.html
and a list of the developer posts is visible on the developer page at
http://localhost:4000/developer/
However, the list isn't visible on github pages and I can't access the post at the url. The blog otherwise works fine on github pages i.e. all the site.posts on the homepage are visible etc.
Note, I did push the files to github. I can see them in the repo.