Escape key handling fix

Ben Ford pointed out that the escape key can cause things to go a little
awry, I've fixed that and added another fix for potential breakage that
hadn't come up before.

CHANGELOG

@@ -1,3 +1,9 @@
+v0.4.1
+======
+It looks like the last release was actually pretty bug-free, aside
+from one tiny bug that NEVER ACTUALLY HAPPENS but someone was bugging
+me about it anyway, oh well.
+
 v0.4.0
 ======
 It's been quite a long time since the last update, due to several

bpython.py

@@ -1,5 +1,5 @@
 #!/usr/bin/env python
-# bpython 0.4.0::fancy curses interface to the Python repl::Bob Farrell 2008
+# bpython 0.4.2::fancy curses interface to the Python repl::Bob Farrell 2008
 #
 # The MIT License
 # 
@@ -819,6 +819,9 @@ class Repl:
 
         y, x = self.scr.getyx()
 
+        if not self.s:
+            return
+
         if x == self.ix and y == self.iy:
             return
 
@@ -864,6 +867,8 @@ class Repl:
             self.clrtobol()
             self.c = '\n'
             # Don't return; let it get handled
+        if self.c == chr( 27 ):
+            return ''
 
         if self.c in ( chr(127), 'KEY_BACKSPACE' ):
             self.bs()