schnuersi said:

Basically every government has such rules.

Yes, but not every governments signed a treaty to explicitly avoid this pitfall (for France and Germany, it's the "Schmidt-Debré" MoU of 1971-72), and this treaty says that neither the French, nor the German government, should block exports of common products to third parties...

EmericD said:

Yes, but not every governments signed a treaty to explicitly avoid this pitfall (for France and Germany, it's the "Schmidt-Debré" MoU of 1971-72), and this treaty says that neither the French, nor the German government, should block exports of common products to third parties...

To my knowledge the Smidt-Debré treaty is still in effect. I also don't know any examples of when Germany blocked the export of a common product to a third party.
What I do know is that this treaty is highly controversial in both France and Germany for several reasons. Mostly because the wording of the treaty is so soft it can easily be interpreted in any direction.

schnuersi said:

I also don't know any examples of when Germany blocked the export of a common product to a third party.

Milan ER / Aravis / Cougar helicopters / Meteor missiles...

schnuersi said:

What I do know is that this treaty is highly controversial in both France and Germany for several reasons. Mostly because the wording of the treaty is so soft it can easily be interpreted in any direction.

I don't know the German version of the treaty, but the wording in French is pretty straightforward!

"Aucun des deux gouvernements n'empêchera l'autre d'exporter ou de laisser exporter dans des pays tiers du matériel d'armement issu de développements ou de productions menés en coopération."

EmericD said:

Milan ER / Aravis / Cougar helicopters / Meteor missiles...

As far as I understand none of the above, except for Meteor, are common products covered by the treaty in the first place.

Just mentioning systems is a bit unprecise. The concrete year and customer country would help so I could try look it up.
 

The last project mentioned in official German paper about the treaty is the Tiger. It also mentiones that no request by the French side related to the treaty was ever denied. In some cases there was concideration but the possible deal fell appart befor a decision was made.

But I am not a lawyer and usually steer away from such problems. Its just not worth the headache. Especially if politics are involved as well.
I should also mention that none of this is public knowledge in Germany. I am hearing about this (not the treaty as such but the troubles) for the first time.