Message2706

if the merge file doesn't yet exist, gexpose.py fails with:

Traceback (most recent call last):
  File "gexpose.py", line 641, in <module>
    process(mapping[0], mapping[1], lazy)
  File "gexpose.py", line 567, in process
    result = merge(mergefile, result)
  File "gexpose.py", line 577, in merge
    f = file(filename, 'r')
IOError: [Errno 2] No such file or directory: 

the patch simply checks to see if the file exists first before opening it for reading. If it doesn't exist, then it bootstraps it with just the generated code and begin/end markers