Fix/child export

[pbking]

Fixes issues described in the forum here: https://wordpress.org/support/topic/resulting-zip-file-has-no-name/

This change fixes two issues, both related to exporting CHILD themes.

Testing

• Activate a CHILD theme. For my testing I activated Twenty Twenty Three, changed a background color and (using the CBT wp-admin menu) created a Child Theme of Twenty Twenty Three (called TT Child). I then imported and activated this new child theme.
• Make changes to the newly activated child theme's Global Styles (such as changing the background color).

Scenario 1 (wp-admin interface)

• From the wp-admin CBT menu export the current theme.
• The theme exported should have the correct filename (such as tt4child.zip) rather than an incomplete file (such as .zip as was reported).
• The contents of the .zip file should be ONLY those resources necessary for the child theme (no unnecessary templates, etc that are contained in the parent theme). (This had previously worked as expected, there should be no change here.)

Scenario 2 (Site Editor interface)

• From the Site Editor CBT menu export the current theme.
• The theme exported should have the correct filename. (This previously worked as expected, there should be no change here.)
• The contents of the .zip file should be ONLY those resources necessary for the child theme (no unnecessary templates, etc that are contained in the parent theme).

[mikachan]

Nice, this is testing well for me! Here's my test report:

I ran through your testing instructions without this PR and can confirm I could reproduce the issues you mentioned.

Then with this PR:

Scenario 1 (wp-admin interface)

From the wp-admin CBT menu export the current theme.

• The theme exported should have the correct filename (such as tt4child.zip) rather than an incomplete file (such as .zip as was reported). ✅
• The contents of the .zip file should be ONLY those resources necessary for the child theme (no unnecessary templates, etc that are contained in the parent theme). ✅

Scenario 2 (Site Editor interface)

From the Site Editor CBT menu export the current theme.

• The theme exported should have the correct filename. ✅
• The contents of the .zip file should be ONLY those resources necessary for the child theme (no unnecessary templates, etc that are contained in the parent theme). ✅

[mikachan]

It's maybe worth mentioning that I've only tested using TT3 - maybe it's worth testing this with at least one other theme.

[pbking]

I just tested with Geologist (a blockbase child) and it all worked as I expected in both interfaces. That's about the most complex child theme relationship we have and considering that I think we're safe to bring this in.