where options is the bitwise-or of:
`RUN_SETUP`::
-
- Make sure there is a Git directory to work on, and if there is a
- work tree, chdir to the top of it if the command was invoked
- in a subdirectory. If there is no work tree, no chdir() is
- done.
+ If there is not a Git directory to work on, abort. If there
+ is a work tree, chdir to the top of it if the command was
+ invoked in a subdirectory. If there is no work tree, no
+ chdir() is done.
+
+`RUN_SETUP_GENTLY`::
+ If there is a Git directory, chdir as per RUN_SETUP, otherwise,
+ don't chdir anywhere.
`USE_PAGER`::