Regular expression denial of service in dparse

dparse is a parser for Python dependency files. dparse in versions before 0.5.2 contain a regular expression that is vulnerable to a Regular Expression Denial of Service. All the users parsing index server URLs with dparse are impacted by this vulnerability. A patch has been applied in version `0.5.2`, all the users are advised to upgrade to `0.5.2` as soon as possible. Users unable to upgrade should avoid passing index server URLs in the source file to be parsed.