Description of problem:
The premier memory leak is reported by Jun'ichi Nomura from NEC Corporation, I can also reproduce the bug on libvirt-python-1.2.8-2.el7.x86_64 via valgrind.

Version-Release number of selected component (if applicable):
libvirt-python-1.2.8-2.el7.x86_64

How reproducible:
always

Steps to Reproduce:
1. # cat demo.py 
#!/usr/bin/env python

import sys
import libvirt

if __name__ == "__main__":
    vm_name = sys.argv[1]
    con = libvirt.open(None)
    dom = con.lookupByName(vm_name)
    dom.XMLDesc()

2. # valgrind -v --leak-check=full --log-file=/tmp/leak /usr/bin/python demo.py <vm_name>

3. # grep 'definitely' /tmp/leak

Actual results:

==14809== 2,407 bytes in 1 blocks are definitely lost in loss record 1,457 of 1,550
==14809==    at 0x4C2845D: malloc (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
==14809==    by 0x5C46624: xdr_string (in /usr/lib64/libc-2.17.so)
==14809==    by 0xCFDE5FD: xdr_remote_nonnull_string (remote_protocol.c:31)
==14809==    by 0xCFE0948: xdr_remote_domain_get_xml_desc_ret (remote_protocol.c:1617)
==14809==    by 0xCFF4FF1: virNetMessageDecodePayload (virnetmessage.c:407)
==14809==    by 0xCFEB06B: virNetClientProgramCall (virnetclientprogram.c:379)
==14809==    by 0xCFC28B1: callFull.isra.2 (remote_driver.c:6625)
==14809==    by 0xCFCC0F4: remoteDomainGetXMLDesc (remote_driver.c:6647)
==14809==    by 0xCF8488C: virDomainGetXMLDesc (libvirt.c:4380)
==14809==    by 0xCC2CE0F: libvirt_virDomainGetXMLDesc (libvirt.c:1141)
==14809==    by 0x4F12B93: PyEval_EvalFrameEx (in /usr/lib64/libpython2.7.so.1.0)
==14809==    by 0x4F141AC: PyEval_EvalCodeEx (in /usr/lib64/libpython2.7.so.1.0)


Expected results:
Fix this.

Additional info: