Organelle suggestion run can fail with collection modified exception

[hhyyrylainen]

When I was building a really big cell quickly with symmetry I ran into the following exception:

My hunch is that there's a problem where the pristine species copy can be updated while there is a suggestion run currently happening, that should be prevented and instead relying on the suggestion timer to try to start it again later.

I put this as low priority as this is the first time I'm seeing this error so it can't be too common.