updated for version 7.4.381
Problem:    Get u_undo error when backspacing in Insert mode deletes more than
            one line break. (Ayberk Ozgur)
Solution:   Also decrement Insstart.lnum.
diff --git a/src/edit.c b/src/edit.c
index 69679bc..6bc517e 100644
--- a/src/edit.c
+++ b/src/edit.c
@@ -8833,6 +8833,7 @@
 		return FALSE;
 	    --Insstart_orig.lnum;
 	    Insstart_orig.col = MAXCOL;
+	    Insstart = Insstart_orig;
 	}
 	/*
 	 * In replace mode: