Shiny Updates: Plugins installed on Multisite shouldn't auto-activate on the primary site

[DrewAPicture]

In testing the installation part of the new shiny updates functionality in trunk, I discovered that installing a plugin via the Network Admin ended up installing the plugin and auto-activating it on the primary site. Probably shouldn't do that.

Steps to reproduce (multisite required):

1. Navigation to Network Admin > Plugins > Add New
2. Install a new plugin by clicking the "Install Now" button
3. AJAX in the button should indicate the plugin is being installed
4. Navigate to Primary Site > Plugins
5. Note that the recently-installed plugin has been installed and is activated

[ianmjones]

When installing a plugin via AJAX request, do not auto-activate if Multisite.

[jeremyfelt]

In 31511:

Do not activate plugins on initial installation in multisite.

Check is_multisite() before activating a plugin that has been installed via AJAX. Without this check, the plugin would be automatically activated on the main site of the network.

Props ianmjones.

Fixes #31327.

[jeffmcneill]

I just experienced this behavior with the latest shiny updates 2-20160606 and the latest wordpress multisite. 4.5.2.

• Go to network plugins
• Add plugin
• Install plugin
• Activate plugin

-- Expected behavior: network activation, and stay on Install Plugin page
-- Actual behavior: ejected to main site of the multisite plugin page, and main site has the plugin activated, network is not activated

[ocean90]

@jeffmcneill Please report issues with the plugin at ​https://github.com/obenland/shiny-updates/issues.