util: fix check for iscsi initiator copy

virStorageSourceInitiatorCopy propagates the return
value from VIR_STRDUP, which returns 1 on a successful
copy.

Only error out on < 0, not non-zero values.

Fixes: 9ea3fdc6Signed-off-by: NJán Tomko <jtomko@redhat.com>
Reviewed-by: NMichal Privoznik <mprivozn@redhat.com>

src/util/virstoragefile.c

@@ -2331,7 +2331,7 @@ virStorageSourceCopy(const virStorageSource *src,
         !(def->pr = virStoragePRDefCopy(src->pr)))
         return NULL;
 
-    if (virStorageSourceInitiatorCopy(&def->initiator, &src->initiator))
+    if (virStorageSourceInitiatorCopy(&def->initiator, &src->initiator) < 0)
         return NULL;
 
     if (backingChain && src->backingStore) {