Fix error in costructor

# Please enter the commit message for your changes. Lines starting
# with '#' will be ignored, and an empty message aborts the commit.
# On branch master
# Your branch is up-to-date with 'origin/master'.
#
# Changes to be committed:
#	modified:   ConsistentHash.pm
#
# Untracked files:
#	../../.t.pl.swp
#	../../t.pl
#
