Revise description of dumbdbm.open() to reflect that the flag argument is

ignored and that mode was ignored before Python 2.2.
This closes SF bug #490098.

Doc/lib/libanydbm.tex

@@ -71,17 +71,17 @@ should only be used when no other DBM-style database is available.
 
 
 \begin{funcdesc}{open}{filename\optional{, flag\optional{, mode}}}
-Open the database file \var{filename} and return a corresponding object.
-The optional \var{flag} argument can be
-\code{'r'} to open an existing database for reading only,
-\code{'w'} to open an existing database for reading and writing,
-\code{'c'} to create the database if it doesn't exist, or
-\code{'n'}, which will always create a new empty database.  If not
-specified, the default value is \code{'r'}.
+Open the database file \var{filename} and return a corresponding
+object.  The \var{flag} argument, used to control how the database is
+opened in the other DBM implementations, is ignored in
+\module{dumbdbm}; the database is always opened for update, and will
+be created if it does not exist.
 
 The optional \var{mode} argument is the \UNIX{} mode of the file, used
 only when the database has to be created.  It defaults to octal
 \code{0666} (and will be modified by the prevailing umask).
+\versionchanged[The \var{mode} argument was ignored in earlier
+                versions]{2.2}
 \end{funcdesc}
 
 \begin{excdesc}{error}