Apply by doing:
       cd /usr/src
       patch -p0 < 020_cvs.patch

And then rebuild and install cvs:
       cd gnu/usr.bin/cvs
       make -f Makefile.bsd-wrapper obj
       make -f Makefile.bsd-wrapper
       make -f Makefile.bsd-wrapper install

Index: gnu/usr.bin/cvs/src/server.c
===================================================================
RCS file: /cvs/src/gnu/usr.bin/cvs/src/server.c,v
retrieving revision 1.26
diff -u -r1.26 server.c
--- gnu/usr.bin/cvs/src/server.c        29 Sep 2001 00:00:39 -0000      1.26
+++ gnu/usr.bin/cvs/src/server.c        21 Jan 2003 03:32:23 -0000
@@ -977,9 +977,6 @@
       return;
    }

-    if (dir_name != NULL)
-       free (dir_name);
-
    dir_len = strlen (dir);

    /* Check for a trailing '/'.  This is not ISDIRSEP because \ in the
@@ -994,6 +991,9 @@
                    "E protocol error: invalid directory syntax in %s", dir);
       return;
    }
+
+    if (dir_name != NULL)
+       free (dir_name);

    dir_name = malloc (strlen (server_temp_dir) + dir_len + 40);
    if (dir_name == NULL)