This issue can be related to "net/http" and not just to "net/http/httputil", depends where the redirection logic is contained.

What version of Go are you using (go version)?

go version go1.10 linux/amd64

Does this issue reproduce with the latest release?

Yes

What operating system and processor architecture are you using (go env)?

GOARCH="amd64"
GOBIN=""
GOCACHE="/home/labkode/.cache/go-build"
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/home/labkode/go/"
GORACE=""
GOROOT="/usr/local/go"
GOTMPDIR=""
GOTOOLDIR="/usr/local/go/pkg/tool/linux_amd64"
GCCGO="gccgo"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/labkode/go-build124504389=/tmp/go-build -gno-record-gcc-switches"

What did you do?

When using the reverse proxy from "net/http/httputil", non normalized urls (containing a dot character) get a redirection to a wrong path that that starts with /@/

ip  - - [16/Jul/2018:14:21:17 +0200] "GET /cernbox/doc/Linux/repo/Ubuntu_18.04/./amd64/ocqt562%2b240-libqt5core5a_5.6.2-14%2b6.17_amd64.deb HTTP/1.1" 301 128
ip  - - [16/Jul/2018:14:21:17 +0200] "GET /@/cernbox/doc/Linux/repo/Ubuntu_18.04/amd64/ocqt562+240-libqt5core5a_5.6.2-14+6.17_amd64.deb HTTP/1.1" 404 290

What did you expect to see?

When the url is normalized by removing the dot character (.) before amd64, the request is fine.

ip  - - [16/Jul/2018:14:28:40 +0200] "GET /cernbox/doc/Linux/repo/Ubuntu_18.04/amd64/ocqt562%2b240-libqt5core5a_5.6.2-14%2b6.17_amd64.deb HTTP/1.1" 200 1831744

What did you see instead?

301 redirection to wrong place