Merge lp:~adeuring/lp-dev-utils/select.error-withour-errno-attr into lp:lp-dev-utils

This morning I got an AttributeError while trying to start an EC2 test. The error occured in line 669 of ec2test/instance.py:

    665 while 1:
    666 try:
    667 select.select([session], [], [], 0.5)
    668 except (IOError, select.error), e:
    669 if e.errno == errno.EINTR:
    670 continue

Poking around in the C source of the select module showed that select.error exceptions are always raised by calling PyErr_SetFromErrno(SelectError). (Well, OK, for Windows, another function is used, but I think we can ignore that here.) From the documentation of this function (http://docs.python.org/c-api/exceptions.html#PyErr_SetFromErrno):

 "This is a convenience function to raise an exception when a C library function has returned an error and set the C variable errno. It constructs a tuple object whose first item is the integer errno value and whose second item is the corresponding error message..."

So, no attribute named "value". But e[0] is an integer with the value of the C errno variable.

I left the old attempt to access e.errno in the code because I don't know if some older version of Python may have generated a error object with the attribute errno.