+--keep-boundaries
+: if multiple filenames are given on the command line,
+ they are normally concatenated together as if the
+ content all came from a single file. That is, the
+ set of blobs/trees produced is identical to what it
+ would have been if there had been a single input file.
+ However, if you use `--keep-boundaries`, each file is
+ split separately. You still only get a single tree or
+ commit or series of blobs, but each blob comes from
+ only one of the files; the end of one of the input
+ files always ends a blob.
+