Comment 7 for bug 1544480

The following worked for me:

Add to each affected /etc/fsab line:

comment=systemd.automount

So, for example:
//192.168.1.100/shared /media/shared cifs comment=systemd.automount,credentials=

Source:
http://lifeisabug.com/fix-debian-wheezy-mounting-cifs-smb-shares-boot-time/

Related bug:
https://bugs.launchpad.net/ubuntu/+source/cifs-utils/+bug/1544546