Invariant documented for `rqPathInfo` doesn't always hold

[hvr]

Not sure if this is a documentation bug or an issue in addRoutes

The documentation specifies the invariant

snap-core/src/Snap/Internal/Http/Types.hs

Lines 462 to 470 in 0b45d71

	-- The following identity holds:
	--
	-- > rqURI r == S.concat [ rqContextPath r
	-- > , rqPathInfo r
	-- > , let q = rqQueryString r
	-- > in if S.null q
	-- > then ""
	-- > else S.append "?" q
	-- > ]

However, I have noticed when mounting a path via

addRoutes [("/foo/",   fooHandler]

that when dumping the request paths via

    liftIO (print rq)
    liftIO (print $ ((rqContextPath rq, rqPathInfo rq, rqQueryString rq), rqURI rq))

You can see that the invariant breaks for the GET /foo HTTP/1.1 corner case:

GET /foo HTTP/1.1
accept: */*
user-agent: curl/7.58.0
host: localhost:8080

sn="localhost:8080" c=127.0.0.1:52732 s=127.0.0.1:8080 ctx=/foo/ clen=n/a
(("/foo/","",""),"/foo")

GET /foo/ HTTP/1.1
accept: */*
user-agent: curl/7.58.0
host: localhost:8080

sn="localhost:8080" c=127.0.0.1:52734 s=127.0.0.1:8080 ctx=/foo/ clen=n/a
(("/foo/","",""),"/foo/")

GET /foo// HTTP/1.1
accept: */*
user-agent: curl/7.58.0
host: localhost:8080

sn="localhost:8080" c=127.0.0.1:52736 s=127.0.0.1:8080 ctx=/foo/ clen=n/a
(("/foo/","/",""),"/foo//")

GET /foo/// HTTP/1.1
accept: */*
user-agent: curl/7.58.0
host: localhost:8080

sn="localhost:8080" c=127.0.0.1:52738 s=127.0.0.1:8080 ctx=/foo/ clen=n/a
(("/foo/","//",""),"/foo///")

[hvr]

Another corner-case where it doesn't hold:

GET /foo? HTTP/1.1
accept: */*
user-agent: curl/7.58.0
host: localhost:8080

sn="localhost:8080" c=127.0.0.1:52834 s=127.0.0.1:8080 ctx=/foo/ clen=n/a
(("/foo/","",""),"/foo?")

[mightybyte]

Pinging @gregorycollins