description:
change-media with --print-xml will produce a disordered xml segment.


Versions:
libvirt-1.2.14-1.el7.x86_64
kernel-3.10.0-246.el7.x86_64
qemu-kvm-rhev-2.3.0-1.el7.x86_64

Repro steps:
1. start a vm with empty cdrom
[root@yisun]#virsh dumpxml vm1 | grep cdrom -A10
    <disk type='file' device='cdrom'>
      <driver name='qemu' type='raw'/>
      <backingStore/>
      <target dev='hdb' bus='ide'/>
      <readonly/>
      <alias name='ide0-0-1'/>
      <address type='drive' controller='0' bus='0' target='0' unit='1'/>
    </disk>
...
2. use "change-media --insert" to insert a disk with "--print-xml"
[root@yisun]# virsh change-media vm1 hdb /tmp/a.iso --insert --print-xml
<disk type="file" device="cdrom">
      <driver name="qemu" type="raw"/>
      <backingStore/>
      <target dev="hdb" bus="ide"/>
      <readonly/>
      <alias name="ide0-0-1"/>
      <address type="drive" controller="0" bus="0" target="0" unit="1"/>
    <source file="/tmp/a.iso"/></disk>

Actual result:
 <source file="/tmp/a.iso"/>  inserted in the same line with </disk> without line break.

Expected result:
format should be like following:
 <disk type='file' device='cdrom'>
      <driver name='qemu' type='raw'/>
      <source file='/tmp/a.iso'/>    <=== put it here as what happens for cdrom insertion without "--print-xml"
      <backingStore/>
      <target dev='hdb' bus='ide'/>
      <readonly/>
      <alias name='ide0-0-1'/>
      <address type='drive' controller='0' bus='0' target='0' unit='1'/>
 </disk>

Additional info:
this also reproducible for "virsh change-media ... --update --print-xml"