sub usage
{
die <<EOT;
-Usage: patch-update [OPTIONS]
-
---gen[=DIR] Include generated files. Optional dest DIR overrides "patches".
---skip-check Skip the check that ensures starting with a clean branch.
+Usage: patch-update [OPTIONS] [patches/DIFF...]
+
+Options:
+-b, --branch=BRANCH The master branch to merge into the patch/* branches.
+ --gen[=DIR] Include generated files. Optional destination DIR
+ arg overrides the default of using the "patches" dir.
+ --skip-check Skip the check that ensures starting with a clean branch.
+-s, --shell Launch a shell for every patch/* branch updated, not
+ just when a conflict occurs.
+-h, --help Output this help message.
EOT
}