OK, had a play with the mirrors on my Laguna2 over the w/e.
As you say, the mechanism stops folding when the resistance from the door is reached.
When I folded my mirror forwards (so it was not usable) it still folded all the way to the door, and when deployed again, went back to the "overly opened" position. Mind you, after a couple of cycles, it was almost back to the right position, and when I pushed it to the detente, it all clicked to the right place and ran as normal. (nice that it didn't get broken!
So it sounds like the open position detection is not working as required.
Whilst I have changed the mirrors on my car, and so have had the housing in component bits (even removing the star washer to change the mounting) I have not stripped out the motor itself. But I know that the motor has only two wires, and that there is no position detection for the mirror body position. (The mirrors within the body may have position feedback, if you have memories for seat position; this is a different thing)
Hence I think that the position for fully open must either be an end-of-travel (EOT) switch within the motor (for the deployed), or current limiting (for the closed, and probably your open position).
So, back to the basics; deploy the mirror, and check that it is at its detente position. Manually pull it to fully closed, then electrically fold it (will stop almost immediately) and electrically deploy again. Once fully deployed, manually pull it closed, to see if thedetente position is beyond the current physical position. By repeated use of the motor and manual movements, you should be able to check all around the shaft, and be sure of the correct detente position for the motor output.
If the detente is weak, and doesn't really stop you turning the mirror on the shaft, then probably the star-lock that holds the spring has slipped. You can strip the carcase of the mirror to see this quite simply, and will then have hands-on to replace the star-lock so the spring is working properly.
Oh, one other test; deploy the mirrors, and then put a meter across the folding motor for the left mirror, to see if there is a switch active there. I suspect, with the gearing used, that the motor cannot have a switch, and that the detente will be the trigger for the over-current stop detection.
If the right mirror is correctly aligned with the detente, and electrically the left mirror shows a switch should be active, but the right mirror does not have that working switch, then you're going to have to go into the motor to have a look for switches. Get a replacement star-lock washer (I'll check the size when I get home) since you will have to break the fitted one to disassemble.
And then get ready for a slightly fiddly session, taking things to bits that are not on Renault's repair list. Most of it will be quite simple (with a bit of care to avoid breaking off plastic tabs, all of which can be seen and released before pulling the cover off) and eventually you will get in to the motor itself, which may be quite a bit more fiddly!