patch 7.4.691 for Problem: Can't build with MzScheme.
Solution:   Change "cwd" into the global variable "start_dir".
diff --git a/src/version.c b/src/version.c
index a847921..1ae5f37 100644
--- a/src/version.c
+++ b/src/version.c
@@ -742,6 +742,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    691,
+/**/
     690,
 /**/
     689,