Stamp HEAD as 9.3devel.

Let the hacking begin ...

src/tools/version_stamp.pl

@@ -23,7 +23,7 @@
 # Major version is hard-wired into the script.  We update it when we branch
 # a new development version.
 $major1 = 9;
-$major2 = 2;
+$major2 = 3;
 
 # Validate argument and compute derived variables
 $minor = shift;