Singularity images may get annexed by datalad-container

[adswa]

Origin: datalad/datalad-container#197

This is a seemingly long standing issue, reraised (including a PR!) by a user, and originally reported already 2021 by @mih datalad/datalad-container#149:

if one adds a container in a plain git repo, the image will be put into Git - this behavior is suboptimal given the size that container images usually take up.
The associated PR is stuck, I inquired what kind of help I or others could provide to get it unstuck.

TODO (not necessarily to be performed in this order)

• Inform OP/Add reference to this issue at origin
• Clarifying Qs asked or not needed
• Nature of the issue is understood
• Inform OP about resolution

[adswa]

I also voiced my opinions on the PR