Installation hangs under Jessie

The installation of Percona Server 5.7 from the apt repository hangs under Debian Jessie and cannot even be cancelled by Ctrl+C. Once the installation starts, I am asked for the root password and its confirmation, then the installer continues and suddenly asks for a password:

smares@smares:/etc$ sudo apt-get install percona-server-server-5.7
Reading package lists... Done
Building dependency tree 
Reading state information... Done
The following extra packages will be installed:
percona-server-client-5.7 percona-server-common-5.7
The following NEW packages will be installed:
percona-server-client-5.7 percona-server-common-5.7
percona-server-server-5.7
0 upgraded, 3 newly installed, 0 to remove and 0 not upgraded.
Need to get 0 B/26,1 MB of archives.
After this operation, 206 MB of additional disk space will be used.
Do you want to continue? [Y/n]
Preconfiguring packages ...
Selecting previously unselected package percona-server-common-5.7.
(Reading database ... 25308 files and directories currently installed.)
Preparing to unpack .../percona-server-common-5.7_5.7.17-11-1.jessie_amd64.deb ...
Unpacking percona-server-common-5.7 (5.7.17-11-1.jessie) ...
Selecting previously unselected package percona-server-client-5.7.
Preparing to unpack .../percona-server-client-5.7_5.7.17-11-1.jessie_amd64.deb ...
Unpacking percona-server-client-5.7 (5.7.17-11-1.jessie) ...
Processing triggers for man-db (2.7.0.2-5) ...
Setting up percona-server-common-5.7 (5.7.17-11-1.jessie) ...
Selecting previously unselected package percona-server-server-5.7.
(Reading database ... 25430 files and directories currently installed.)
Preparing to unpack .../percona-server-server-5.7_5.7.17-11-1.jessie_amd64.deb ...
Unpacking percona-server-server-5.7 (5.7.17-11-1.jessie) ...
Processing triggers for systemd (215-17+deb8u6) ...
Processing triggers for man-db (2.7.0.2-5) ...
Setting up percona-server-client-5.7 (5.7.17-11-1.jessie) ...
Setting up percona-server-server-5.7 (5.7.17-11-1.jessie) ...
Password:

No matter what I enter there, nothing happens. I assume this is related to the fact that I disabled the ability to su without password by commenting out

auth sufficient pam_rootok.so

in /etc/pam.d/su and uncommenting

auth required pam_wheel.so

.