Binder link generation bug on jupyterhub.github.io/nbgitpuller/link

[jreades]

Bug description

On the Binder tab for https://jupyterhub.github.io/nbgitpuller/link setting a branch on the Git Environment Repo also sets the same branch on the Git Content Repo in the generated URL even when this is not intended (i.e. branch for Content Repo is left as master).

Expected behaviour

Using the following parameters:

• BinderHub URL: https://mybinder.org
• Git Environment Repo: https://github.com/kingsgeocomp/code-camp-env
• Branch: notebook-v1.0
• Git Content Repo: https://github.com/kingsgeocomp/code-camp
• File to open: N/A
• Application ot Open: Classic Jupyter Notebook

I would expect the autogenerated link to be:
https://mybinder.org/v2/gh/kingsgeocomp/code-camp-env/notebook-v1.0?urlpath=git-pull%3Frepo%3Dhttps%253A%252F%252Fgithub.com%252Fkingsgeocomp%252Fcode-camp%26urlpath%3Dtree%252Fcode-camp%252F%26branch%3Dmaster

I can edit the link manually (as I have done here) and obtain the correct behaviour.

Additionally, some quick checking suggests that:

1. Specifying a branch on the Git Content Repo but not the Environment Repo does not update the Binder link with the branch information for the content. The URL remains unchanged.
2. Having different branches specified for the Environment and Content repos results in the Binder link having the Environment Repo branch specified for both repos.

The fact that the links can be manually corrected to do the 'right' thing suggests to me that it's a 'simple' JavaScript issue on the link page (I've not touched JS since about version 1.1 so I'm not keen to start now). I don't have any other platforms on which to test to see if it's somehow specific to Chrome on OSX.

Actual behaviour

The link that was actually generated was:
https://mybinder.org/v2/gh/kingsgeocomp/code-camp-env/notebook-v1.0?urlpath=git-pull%3Frepo%3Dhttps%253A%252F%252Fgithub.com%252Fkingsgeocomp%252Fcode-camp%26urlpath%3Dtree%252Fcode-camp%252F%26branch%3Dnotebook-v1.0

How to reproduce

1. Go to https://jupyterhub.github.io/nbgitpuller/link
2. Click on 'Binder'
3. Set the parameters as above.
4. Copy+Paste Link

Your personal set up

• OS: OSX

• Version: 10.14.6 Mojave

• Browser uised: Chrome Version 81.0.4044.138 (Official Build) (64-bit)

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[GeorgianaElena]

Thanks a lot for reporting the bug @jreades! ❤️

I've opened #138 to fix this. There is a link in the PR description where you can test the changes if you want to check it out.

[jreades]

Awesome, looks good to me. Thank you for the quick fix!