Starting with PostgreSQL 12, pg_restore refuses to run when neither -d
nor -f are specified (c.f. commit 413ccaa74d9a), and it also makes "-f -"
mean the old implicit behavior of dumping to stdout. However, older
branches write to a file called ./- when invoked like that, making it
impossible to write pg_restore scripts that work across versions. This
is a partial backpatch of the aforementioned commit to all older
supported branches, providing an upgrade path.