Description of problem:
on line 4322 of libvirt-php.c, in the libvirt_domain_disk_add function, there is are two consecutive calls to virDomainFree, the first freeing the domain resource, therefore causing the second call to fail always.

Version-Release number of selected component (if applicable):
commit id: 9f355ebed7a217669269c1a4016329f7411e356b

How reproducible:
Can reproduce by calling libvirt_domain_disk_add with valid parameters

Steps to Reproduce:
1. Set up libvirtd, create a domain and try to add a disk to it using libvirt_domain_disk_add
2. Observe the error message.

Actual results:
invalid connection pointer in virDomainFree

Expected results:
in libvirt-php debug log
libvirt_domain_disk_add: Domain <resource> freed
libvirt_domain_disk_add: returning 0x269a0c0


Additional info:
I have made the change of commenting out line 4322, which fixed the error