inst.reason isn't alway in the form (errno, strerror)
urllib2.urlopen("foobar://foo") is an example
where inst.reason is a string
fix issue383
foo renamed from bar:26d3ca0dfd18e44d796b564e38dd173c9668d3a9
rev offset length base linkrev nodeid p1 p2
0 0 6 0 0 26d3ca0dfd18 000000000000 000000000000
1 6 7 1 1 d267bddd54f7 26d3ca0dfd18 000000000000