tdf#124318 FILEOPEN: XLS Hyperlink URL incorrect

regression from
    commit 52f69445c55c9af8ad97bee6da335b4592d56d4d
    Date:   Wed Aug 1 17:03:18 2018 +0200
    loplugin:stringloop in sc

Change-Id: I7d481ea27866fc146c5de9d027aa7bb308f14e52
Reviewed-on: https://gerrit.libreoffice.org/69652
Tested-by: Jenkins
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>
diff --git a/sc/source/filter/excel/xistream.cxx b/sc/source/filter/excel/xistream.cxx
index 6decac3..d5f8c1e 100644
--- a/sc/source/filter/excel/xistream.cxx
+++ b/sc/source/filter/excel/xistream.cxx
@@ -871,7 +871,9 @@
        }

        *pcEndChar = '\0';
        aRet.append( pcBuffer.get(), pcUniChar - pcBuffer.get()  );
        // this has the side-effect of only copying as far as the first null, which appears to be intentional. e.g.
        // see tdf#124318
        aRet.append( pcBuffer.get() );

        nCharsLeft = nCharsLeft - nReadSize;
        if( nCharsLeft > 0 )