1377 blacklist dependencies

Latest comments addressed. 
Ignore function fixed. Was not working while writing to the exclude file. 
if the file is opened for appending using either 'a' or 'a+', any seek() operations will be undone at the next write which write an useless file. 
http://www.tutorialspoint.com/python/file_seek.htm 

Why moving the invocation of `truncate()`?