Comment # 14 on bug 1197723 from Cosmin Tanczel

Ok, found some spare time:

It seems after the last update we enable pcscd.service by default at boot time.
On the computer that was not updated and gpg works (detects the cards), the
pcscd service is NOT enabled by default at boot time.

So this is what it was changed.

Anyways... it should also work with pcscd service enabled, but I think the
service is starting with 'disable-ccid' instead of 'pcsc-shared'. And ... to be
honest, I am not sure how secure it is to start with pcsc-shared, because if we
start it with pcsc-share, scdaemon gets exclusive access to the card and for it
can cache some information from the card.

But again... I am just a user, so I am not sure if what I said above makes any
sense for you :)

Bottom line, after the last update we enable pcscd.service by default and this
makes gpg not able to detect the card, so the solution was to disable this
service. 

I think it's just a workaround since pcscd service might be used for something
else, so it's not really a solution for those who really need it.

But again... I am just a user, so I am not sure if what I said above makes any
sense for you :)

Please let me know if I can provide any other information to get this solved.

Thank you!