Opening github from the toolbar doesn't open after closing pane #891

Prerequisites

• Have you tried to reproduce the problem in Safe Mode?
• Have you followed all applicable steps in the debugging guide?
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Description

Opening Github or Git Pane after closing the pane adds the pane back to the dock, but doesn't open the dock until you click again.

Steps to Reproduce

1. Open Atom.
2. If github package is open, close it by right clicking and clicking close pane
3. On the bottom right click on the [0-9]+ files

Expected behavior:
[What did you expect to happen?]
Opens the git panel

Actual behavior:
[What actually happened instead?]
Nothing happens or it seems that way, but actually the git panel gets added to the dock on the right but it's closed.

Reproduces how often:
[What percentage of the time does this happen?]
100%

Versions

You can get this information from copy and pasting the output of atom --version and apm --version from the command line. Also, please include the OS and what version of the OS you're running.

Atom    : 1.19.0-dev-58313f6ab
Electron: 1.6.9
Chrome  : 56.0.2924.87
Node    : 7.4.0

Additional Information

gif:

Please include any additional information, configuration or data that might be necessary to reproduce the issue. Screenshots, if appropriate, are helpful as well.

If your issue involves a repository, and that repository is public, please include a link to it.

I noticed this while testing fix for #872
/cc @smashwilson