r23668: When creating a new string value, win2k regedit delivers

r23668: When creating a new string value, win2k regedit delivers
one byte of data despite characters being two-byte.

This modifies registry_pull_value, to change the data
to the correct two-byte version of the empty string,
(as delivered by winxp), when only one byte of data is
received.

Michael
(This used to be commit a4c2b20296d6853cd1578601f17330cde75c4038)