This patch was developed by a customer at New York University, as part of
the analysis of a bug that was only discovered because the customer was
building procmail as root, triggering TOGGLE_SGID_OK to be set, which in
turn triggered CAN_toggle_sgid to be set, which is checked via logical OR
with accspooldir when deciding about the privileges needed to set[rg]id.
The patch will be submitted upstream.

--- procmail-3.22/src/foldinfo.c.orig	2001-09-10 21:57:32.000000000 +0000
+++ procmail-3.22/src/foldinfo.c	2017-04-03 09:35:21.186639287 +0000
@@ -185,9 +185,9 @@
      *chp='\0';					   /* strip off the filename */
   if(!stat(buf,&stbuf))
    { unsigned wwsdir;
-     accspooldir=(wwsdir=			/* world writable spool dir? */
-	    ((S_IWGRP|S_IXGRP|S_IWOTH|S_IXOTH)&stbuf.st_mode)==
-	     (S_IWGRP|S_IXGRP|S_IWOTH|S_IXOTH)
+     accspooldir=((wwsdir=			/* world writable spool dir? */
+	    (((S_IWGRP|S_IXGRP|S_IWOTH|S_IXOTH)&stbuf.st_mode)==
+	     (S_IWGRP|S_IXGRP|S_IWOTH|S_IXOTH)))
 	  <<1|						 /* note it in bit 1 */
 	  uid==stbuf.st_uid);	   /* we own the spool dir, note it in bit 0 */
      if((CAN_toggle_sgid||accspooldir)&&privileged)