default log message, and before the editor is started.
It takes one to three parameters. The first is the name of the file
-that the commit log message. The second is the source of the commit
+that contains the commit log message. The second is the source of the commit
message, and can be: `message` (if a `-m` or `-F` option was
given); `template` (if a `-t` option was given or the
configuration option `commit.template` is set); `merge` (if the