tail apt.log 
  Holding Back nfs-common rather than change libnfsidmap2
Investigating mount
Package mount has broken dep on nfs-common
  Considering nfs-common 0 as a solution to mount 5115
  Upgrading nfs-common due to Breaks field in mount
Investigating nfs-common
Package nfs-common has broken dep on libnfsidmap2
  Considering libnfsidmap2 0 as a solution to nfs-common 0
  Holding Back nfs-common rather than change libnfsidmap2
Done