"Normalizing" double slashes in HTTP URL paths is incorrect

[notklea]

See why https://runxiyu.org/comp/doubleslash/

It has come to my attention that warcprox does that.

Sample URL:
https://wp-stat.s3.us-east-1.amazonaws.com//ad/public/static/brandconnect/fx/americans/thewashingtonpost.png

[TheTechRobo]

To provide some more information, with curl, I get HTTP 200 on curl https://wp-stat.s3.us-east-1.amazonaws.com//ad/public/static/brandconnect/fx/americans/thewashingtonpost.png -k --head but not when i specify --proxy localhost:8004 (which is where I was running warcprox).

This only seems to happen for leading slashes, based on debugging logs. Any amount of leading slashes disappears. Extra slashes in the middle of the path seem to be passed through fine (at least based on logs). I can't reproduce this on localhost (even after setting allow_localhost to True in the code), and my HTTP server framework of choice (Flask) appears to have the same issue, so it's hard to pinpoint the exact issue.

Browsers do not collapse the leading slash at the start.