With `includeSubdirs` and the destination folder the same as the source
folder, the Export for Screens folder of `a.svg` was `a`, and its
`Artboard-1.svg` replaced the source `a/Artboard-1.svg` before Batch
opened it. Batch now keeps the names of subfolders of the destination
folder that hold source files, so that export folder is `a-2`.