[libvirt] QEMU 1.6 and drive discard parameter

[whitearchey]

In QEMU 1.6 parameters of 'drive' option were removed:

QemuOptsList qemu_drive_opts = {
     .name = "drive",
     .head = QTAILQ_HEAD_INITIALIZER(qemu_drive_opts.head),
     .desc = {
         /*
          * no elements => accept any params
          * validation will happen later
          */
         { /* end of list */ }
     },
};

But libvirt still checks for QEMU_CAPS_DRIVE_DISCARD using QMP  
query-command-line-options:

static struct virQEMUCapsCommandLineProps virQEMUCapsCommandLine[] = {
     { "machine", "mem-merge", QEMU_CAPS_MEM_MERGE },
     { "drive", "discard", QEMU_CAPS_DRIVE_DISCARD },
     { "realtime", "mlock", QEMU_CAPS_MLOCK },
};
...
qemuMonitorGetCommandLineOptionParameters(mon,  
virQEMUCapsCommandLine[i].option, &values)

So, when I try to use discard option in domain xml I get this error:

error : qemuBuildDriveStr:3986 : unsupported configuration: discard is not  
supported by this QEMU binary