Fix the comment on the sqlite3PExpr() subroutine.  Ticket #3924. (CVS 6789)

FossilOrigin-Name: 4bb96db6b4d2cfa71430a2646c1082a494e3519f
diff --git a/src/expr.c b/src/expr.c
index 24fcb4a..e331435 100644
--- a/src/expr.c
+++ b/src/expr.c
@@ -12,7 +12,7 @@
 ** This file contains routines used for analyzing expressions and
 ** for generating VDBE code that evaluates expressions in SQLite.
 **
-** $Id: expr.c,v 1.445 2009/06/01 16:53:10 shane Exp $
+** $Id: expr.c,v 1.446 2009/06/19 18:32:55 drh Exp $
 */
 #include "sqliteInt.h"
 
@@ -490,11 +490,11 @@
 }
 
 /*
-** Allocate a Expr node which joins up to two subtrees.
+** Allocate a Expr node which joins as many as two subtrees.
 **
-** The 
-** Works like sqlite3Expr() except that it takes an extra Parse*
-** argument and notifies the associated connection object if malloc fails.
+** One or both of the subtrees can be NULL.  Return a pointer to the new
+** Expr node.  Or, if an OOM error occurs, set pParse->db->mallocFailed,
+** free the subtrees and return NULL.
 */
 Expr *sqlite3PExpr(
   Parse *pParse,          /* Parsing context */