Repository with trailing slash are archived separately

https://www.github.com/kalpitk/test and https://www.github.com/kalpitk/test/ get archived separately, despite actually being same. -> https://archive.softwareheritage.org/browse/origin/https://github.com/kalpitk/test/directory/ -> https://archive.softwareheritage.org/browse/origin/https://github.com/kalpitk/test//directory/

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Migrated from T1625 (view on Phabricator)