fix 'Source' to 'Package' rename in apt-ftparchive

This rename with value is ordered by the 'old' name 'Source', but should
be ordered by the new name… by splitting the operation in a delete and a
new field we can easily fix this problem locally for now.

ftparchive/writer.cc

@@ -837,7 +837,8 @@ bool SourcesWriter::DoPackage(string FileName)
    // (5 hardcoded + checksums + maintainer + end marker)
    std::vector<TFRewriteData> Changes;
 
-   Changes.push_back(SetTFRewriteData("Source",Package.c_str(),"Package"));
+   Changes.push_back(SetTFRewriteData("Source", 0));
+   Changes.push_back(SetTFRewriteData("Package",Package.c_str()));
    if (Files.empty() == false)
       Changes.push_back(SetTFRewriteData("Files",Files.c_str()));
    if (ChecksumsSha1.empty() == false)