+which rolls the tarball file(../releases/lilypond-0.1.73.tar.gz)
+and leaves your patch as file(./lilypond-0.1.73.jcn1.diff).
+footnote('Make diff' generates a patch between two tarballs. For
+more info type 'make diff help=='. We assume that there is a tarball
+file(lilypond-0.1.73.tar.gz) in the directory file(../releases).
+