+Prepare each commit with its patch since <mine> head forked from
+<his> head, one file per patch, for e-mail submission. Each
+output file is numbered sequentially from 1, and uses the first
+line of the commit message (massaged for pathname safety) as the
+filename.
+
+When -o is specified, output files are created in that
+directory; otherwise in the current working directory.
+
+When -n is specified, instead of "[PATCH] Subject", the first
+line is formatted as "[PATCH N/M] Subject", unless you have only
+one patch.
+
+When --mbox is specified, the output is formatted to resemble
+UNIX mailbox format, and can be concatenated together for
+processing with applymbox.