Fixed MP trees when using alphabets that don't start with a '0'.
Fixed MP trees when using alphabets that don't start with a '0'.

skirsdeda/django-treebeard,tabo/django-treebeard,django-treebeard/django-treebeard,tabo/django-treebeard,django-treebeard/django-treebeard,skirsdeda/django-treebeard,skirsdeda/django-treebeard,skirsdeda/django-treebeard,tabo/django-treebeard,django-treebeard/django-treebeard,tabo/django-treebeard