Uploading image.png using image dialog creates badly named attachments

Reproduction steps:

• use either the new or old image dialog
• make the wiki multi-lingual
• add a new supported language (e.g., fr)
• make the new language the default language
• Create a new page, upload an image named image.png (other filenames works) and insert it using the image dialog
• Save the page

Expected

The attachment name is substituted to the following pattern "${datetool.date.time}-${mathtool.random(100, 1000)}.$extension"

It used to be the case before switching to the temporary upload mechanism, where this logic is currently missing.

Actual results:

The page contains an attachment named {}fileCreatedFromDataURI{}.png

Additional note:

Copy-and-pasted images on windows are always named image.png, leading to the behavior described above for all pasted images.