Translation update runs multiple times when doing bulk upgrade for themes

[ocean90]

I added some log output to Language_Pack_Upgrader::async_upgrade() and these are the results:

With one theme:
First run: ​https://gist.github.com/ocean90/39461005c6088ecd67b5
Second run: ​https://gist.github.com/ocean90/aa63c0f8ad5fdbb979eb

With two themes:
First run: ​https://gist.github.com/ocean90/586e56a265d84e363417
Second run: ​https://gist.github.com/ocean90/2648dff4da960610a4c6
Third run: ​https://gist.github.com/ocean90/8052a9ee88c31299b660

Plugin for comparison: ​https://gist.github.com/ocean90/999c6ee0bab6431cfa3d

So the do_action for upgrader_process_complete in WP_Upgrader::run() is the reason for this. But this is only called when $options['is_multi'] is false. For plugin bulk updates is_multi is set to true. For themes not and currently I have no idea why, maybe dd32 can weigh in here.

Attached patch sets is_multi to true for themes.

[dd32]

Seems pretty straight forward, I can't see any reason why this change would cause a problem.

It looks like it was simply missed when bulk theme updates were added.

[ocean90]

In 29622:

Theme Upgrader: Set is_multi to true when doing bulk upgrades.

fixes #29234.