Searching in documentation in VS2015 leads to Online docs, but concrete look-up leads to local docs

To repro:
0. VS2015 is set as default editor.
1. Open attached project and open ColorizeBell script.
2. Select, e.g. SpriteRenderer.
3. Press Help -> Unity API Reference.
4. Note: UnityFolder/Editor\Data\Documentation\en\ScriptReference\SpriteRenderer.html is opened in VS2015.
5. Return to script and select List.
6. Press Help -> Unity API Reference.
7. Note: http://docs.unity3d.com/ScriptReference/30_search.html?q=List is opened in VS2015.

Actual result: Behaviour is inconsistent within the product -> similar operations give different results.
Expected results:
If offline docs are installed - VS2015 should open them in any case.
If offline docs are not installed - VS2015 should open online docs in any case.