pipe error checking

--HG--
branch : pmacs2

buffer.py

@@ -399,6 +399,9 @@ class ConsoleBuffer(Buffer):
     def readonly(self):
         return True
 
+class InterpreterPipeError(Exception):
+    pass
+
 class InterpreterBuffer(Buffer):
     _basename = 'Interpreter'
     def create_name(cls, parent):
@@ -432,6 +435,8 @@ class InterpreterBuffer(Buffer):
     def get_cmd(self):
         raise Exception, 'unimplemented'
     def pipe_readline(self):
+        if self.pipe.poll() is not None:
+            raise InterpreterPipeError('broken pipe')
         line = self.pipe.stdout.readline()
         m = self.readre.match(line)
         if m: