SB-EXT:RUN-PROGRAM Fails when DIRECTORY is NIL

[Wilfredo Velázquez-Rodríguez]

The documentation for SB-EXT:RUN-PROGRAM states the following:

:directory
  Specifies the directory in which the program should be run. nil (the default) means the directory is unchanged.

This implies that you should be able to explicitly pass DIRECTORY as NIL ala

(run-program "my-program" () :directory nil)

However, doing so signals a type error:

The value NIL
is not of type
  (OR (VECTOR CHARACTER) (VECTOR NIL) BASE-STRING PATHNAME
      FILE-STREAM).
   [Condition of type TYPE-ERROR]

I've attached a simple patch to fix this.

[Stas Boukarev (stassats)]

In 82cd148d729c241e79c8df04b700beec1b7c55de, thanks.