LeftNav/Tabs active selection bugs

[tay1orjones]

Continuing problems we're seeing with the left nav selection states:

1. Duplicate selection when page names are similar (similar to #44)

• 

2. Single pages with tabs lose left nav selection when a tab non-first tab is selected (similar to #168)

• First tab selected, has appropriate active state:
  

• Second tab selected, does not have appropriate active state:
  

[eng618]

Same issue occurs when there is a subfolder in pages/. i.e. pages/notes/myNewNote

The nav will be created but, the entire section is active as below image depicts

[vpicone]

@eng618 is this still an issue for you? We made some changes to the way these are handled.

[eng618]

@vpicone no seems to be resolved.

[SimonFinney]

@vpicone I've observed this issue still existing when pages are named the same, but fall under separate sections - here's an example of it on the Carbon Design System:

[vpicone]

Ah the issue that never ends thank you @SimonFinney will take a look at it!

[tay1orjones]

We're also experiencing an issue where tabbed pages get sent to 404 occasionally when the titles are similar. This is for https://pages.github.ibm.com/ai-applications/design/

Here's the bug report, ai-applications/design#8:

To recreate:
Open this page - https://pages.github.ibm.com/ai-applications/design/team/tools-and-resources/tools
Click on Resources tab
Click on Tools tab = 404 - it's pointing to https://pages.github.ibm.com/ai-applications/design/team/tools-**and-tools**/resources/
Designer toolkit doesn't work either. https://pages.github.ibm.com/ai-applications/design/team/tools-**and-designer-toolkit**/resources/

Is appending the wrong url to the tab link for some reason.