Pasting captioned images generates unexpected wiki syntax

Follow these steps to reproduce:

• copy some content that includes an image with caption; you can use for instance https://en.wikipedia.org/wiki/Design_rule_checking
• edit a wiki page with the WYSIWYG editor
• paste the copied content
• switch to Source and check the generated wiki syntax

Expected: the image caption should end up as image syntax "label", as in [[caption>>image:some.png]]
Actual: the image caption ends up outside the image syntax, as text that follows the image, as in [[image:some.png]] caption here

For instance, by pasting the captioned image from https://en.wikipedia.org/wiki/Design_rule_checking , we get:

[[~[~[image:https://upload.wikimedia.org/wikipedia/commons/thumb/5/5a/The_three_basic_DRC_checks.svg/300px-The_three_basic_DRC_checks.svg.png~|~|height="254" width="300"~]~]>>url:https://en.wikipedia.org/wiki/File:The_three_basic_DRC_checks.svg]]The basic DRC checks - width, spacing, and enclosure