When looking up a lease via omapi, the dhcpd ignores the "state" field
of the query key object.  This can prevent the query from working at
all, because there can easily be multiple objects which are
distinguished only by "state":

> new lease
obj: lease
> set hardware-address = 5a:36:0e:9d:00:01
obj: lease
hardware-address = 5a:36:0e:9d:00:01
> open
can't open object: more than one object matches key
obj: lease
hardware-address = 5a:36:0e:9d:00:01
> set state = 00:00:00:02
obj: lease
hardware-address = 5a:36:0e:9d:00:01
state = 00:00:00:02
> open
can't open object: more than one object matches key
obj: lease
hardware-address = 5a:36:0e:9d:00:01
state = 00:00:00:02
>

This bug seems to be described here:
  https://lists.isc.org/pipermail/dhcp-hackers/2005-August/001399.html

Sadly no-one seems to have given any useful pointers to Robin Breathe
in 2005 and the bug remains unfixed at least in my current distro.

As as result, the "lookup_ip" function in pypureomapi does not work
reliably (and cannot be made to work reliably).

(I'm using Debian's isc-dhcp-server version 4.2.2.dfsg.1-5+deb70u8.)

Ian.