Changelog:
============
-Do not detect as requirements.txt if the file is a python script.
-Provide information of the original line when parsing requirement fails.
-Resolve -r requirements paths relative to the requirement file they are specified
-Updating package now overwrites the old files instead of removing before installing.
Signed-off-by: Wang Mingyu <wangmy@fujitsu.com>
Signed-off-by: Khem Raj <raj.khem@gmail.com>
