Previously, CopyStringVal() mistakenly copies a null
StringVal as an empty string (i.e. a non-null string
with zero length). This change fixes the problem by
distinguishing between these two cases in CopyStringVal()
and handles them properly. Also added a test case for it.
This problem only started showing up recently due to
commit 51268c053f which
calls CopyStringVal() in OffsetFnInit(). All other
pre-existing callers of CopyStringVal() before that
commit checks if 'src' is null before calling it so
the problem never showed up. In that sense, this is
a latent bug exposed by the aforementioned commit.
Change-Id: I3a5b9349dd08556eba5cfedc8c0063cc59f5be03
Reviewed-on: http://gerrit.cloudera.org:8080/5198
Reviewed-by: Michael Ho <kwho@cloudera.com>
Tested-by: Internal Jenkins
b82eed5ee0