format-patch: improve head calculation for cover-letter

diff --git a/run-command.h b/run-command.h
index 850c638f19a2b6776c0311db28371b18438f207a..221ce331405933f6f097b7e2b51401b70097e4e2 100644 (file)
--- a/run-command.h
+++ b/run-command.h
@@ -45,6 +45,7 @@ int start_command(struct child_process *);
 int finish_command(struct child_process *);
 int run_command(struct child_process *);
 
+extern char *find_hook(const char *name);
 extern int run_hook(const char *index_file, const char *name, ...);
 
 #define RUN_COMMAND_NO_STDIN 1