def parse_dependency_links(requirements_files=['requirements.txt',
                                               'tools/pip-requires']):
    dependency_links = []
    # dependency_links inject alternate locations to find packages listed
    # in requirements
    for line in get_reqs_from_files(requirements_files):
        # skip comments and blank lines
        if re.match(r'(\s*#)|(\s*$)', line):
            continue
        # lines with -e or -f need the whole line, minus the flag
        if re.match(r'\s*-[ef]\s+', line):
            dependency_links.append(re.sub(r'\s*-[ef]\s+', '', line))
        # lines that are only urls can go in unmolested
        elif re.match(r'\s*https?:', line):
            dependency_links.append(line)
    return dependency_links