IMHO, this should not work like the bugzilla clone by default. Instead it should:

• Open a new ticket.
• Add a link to the old ticket.
• Possibly add the contents of the initial comment.

It should definitely not add everyone watching the old ticket, or all the contents of the old ticket (thats why we have hyperlinks!) or old tags or blocks or assignees or depends on.

All IMHO.

MHO, this should not work like the bugzilla clone by default. Instead it should:

Open a new ticket.
Add a link to the old ticket.

Agreed.

Possibly add the contents of the initial comment.

Disagreed, please add everything and allow me to filter the contents.

It should definitely not add everyone watching the old ticket

Agreed.

or all the contents of the old ticket (thats why we have hyperlinks!)

Well, reading old ticket through hyperlink would often mean "too much
noise => give up!". I really would rather have the option to filter
the contents accordingly, so the new report is clean and readable.
...

or old tags or blocks or assignees or depends on.

I don't have opinion here.

If the issue is re-opening a closed ticket, to me the solution isn't : clone the ticket, it is: allow the ticket to be re-opened :)

Looking at the code, it seems contributors to the project and the person who opened the ticket are able to re-open it.

I think I'd rather leave it this way, having anyone be able to re-open a closed ticket isn't quite appealing (esp knowing that closed tickets can still be commented on).
If you have the same issue I'd recommend commenting on the ticket (even if it's just to ask for it to be reconsidered) or open a new one.
I don't really like the idea of cloning tickets in general.

What do you think?

what i was looking for was a "move this ticket to another repo" functionality. i.e. it was opened against releng, but should have been opened against infra.

what i was looking for was a "move this ticket to another repo" functionality. i.e. it was opened against releng, but should have been opened against infra.

It's a different use-case than the one originally reported here.
This is more a re-assign feature than a cloning one. My main issue with it would
be: how to prevent it from being abused?

It's a different use-case than the one originally reported here.

should I open a new issue for discussion?

This is more a re-assign feature than a cloning one. My main issue with it would
be: how to prevent it from being abused?

you are worried about "re-assign" being abused?

Looking at the code, it seems contributors to the project and the person who opened the ticket are able to re-open it.

If OP is able to reopen, LGTM (that's what the OP's had in mind in this issue).

Edit: Thinking again, no :( even not authored issues are sometimes worth reopen, and if
this is really not possible, at least clone should be "easy".

Really unsure about this one, I understand that contributors and authors can re-open, personally those are the persons I would expect to do that. Even to a closed issue, comments can still be added. So someone could either add a comment and ask for re-opening the issue, or create a new and refer to the existing one. I don't fully understand the use case for cloning issues.

Going to close it for now, feel free to commend and share your thoughts if it should be re-opened and further discussed.