Inserting captionless and captioned image together causes shortcode to appear in visual mode

[trepmal]

1. select an image with no caption
2. select an image with a caption
3. batch-insert into post

The [caption] shortcode will appear in the visual editor.

​http://screencast.com/t/xk6PD0tIxV

It seems like it's generating the HTML in media-upload.js, around line 368-372, where the code is directly inserted inside of the Visual editor and not evaluated or hidden (and visible only in the Text version).

The wpeditimage plugin searches for captions by checking if the inserted string begins with [caption. With multiple images, we're inserting a single string, which is causing the issue here. Instead, we should be inserting multiple strings.

This can be fixed by going into media-upload.js and changing the insert event callback to use each instead of map, and moving the call to insert into the loop.

In 22672:

Media: Insert each attachment into the editor individually.

This allows the wpeditimage plugin to correctly identify caption shortcodes.

fixes #22459, see #21390.