Unable to push after import because of closed multiple heads
In Heptapod 0.6.0, for imports by URL, protection against multiple heads per branch is temporarily lifted, in order not to block the process, so that the condition can be resolved later.
But after the import, the protection is again in place. The problem is that it doesn't ignore closed heads. For repos with old closed heads, a quite frequent condition of older repositories, all pushes will be refused unless the protection is lifted permanently, which is cumbersome and unsatisfying, and quite obscure, users will believe in good faith that they don't have multiple heads (the purpose of this issue is to make it less obscure).
A patch has been submitted to Mercurial to introduce the appropriate option. In the meanwhile we'll need to backport it in one way or the other and change the default setting in Heptapod.