As a matter of fact, there is more than one discussion about what are the call you can safely do in the constructor.
Someone thinks “avoid all external call”, some other says “avoid to use ‘this’ or address(this)” in the constructor, other are concerned about using ‘this’ after a ‘new’, other want to introduce warning and errors for the ‘this’ use and so on.
On GitHub/Ethereum do exist pages and pages about this, but true conclusions lack.
What is the recommended practice in Solidity? Does exist any list/cheat sheet about that?
EDIT: added some examples of such discussions as per smarx suggestion