Xen4.1 initializes some unspecified sexpr config items to an empty
string, unlike previous Xen versions that would leave the item unset.
E.g. the kernel item for an HVM guest (non-direct kernel boot):
Xen4.0 and earlier
...
(image
(hvm
(kernel )
...
Xen4.1
...
(image
(hvm
(kernel '')
...
The empty string for kernel causes some grief in subsequent parsing
where existence of specified kernel is checked, e.g.
if (!def->os.kernel)
...
This patch solves the problem in sexpr_node_copy() by not copying
a node containing an empty string.
We already have virAsprintf, so picking a similar name helps for
seeing a similar purpose. Furthermore, the prefix V before printf
generally implies 'va_list', even though this variant was '...', and
the old name got in the way of adding a new va_list version.
global rename performed with:
$ git grep -l virBufferVSprintf \
| xargs -L1 sed -i 's/virBufferVSprintf/virBufferAsprintf/g'
then revert the changes in ChangeLog-old.
