Don't walk past the end of ldb values.

Don't walk past the end of ldb values.

This is a partial fix towards bugs due to us walking past the end of
what we think are strings in ldb.  There is much more work to do in
this area.

Andrew Bartlett
(This used to be commit 5805a9a8f35fd90fa4f718f73534817fa3bbdfd2)