cmd/go: mod download uses global gitconfig, should check project's gitconfig first

[genert]

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

go version go1.12.4 darwin/amd64

Does this issue reproduce with the latest release?

Yes

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

go env Output

GOARCH="amd64"
GOBIN=""
GOCACHE="/Users/genertorg/Library/Caches/go-build"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOOS="darwin"
GOPATH="/Users/genertorg/go"
GOPROXY=""
GORACE=""
GOROOT="/usr/local/Cellar/go/1.12.4/libexec"
GOTMPDIR=""
GOTOOLDIR="/usr/local/Cellar/go/1.12.4/libexec/pkg/tool/darwin_amd64"
GCCGO="gccgo"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
GOMOD="/Users/genertorg/masga/gobase/go.mod"
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 -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/tb/3yd9xyqj5cn53csl1k17tmgr0000gn/T/go-build189348569=/tmp/go-build -gno-record-gcc-switches -fno-common"

What did you do?

When using "git config url."[email protected]:".insteadOf https://bitbucket.org/" within project folder, it would be expected that when getting private package within bitbucket SVN, the project's git configuration should be used instead of global git configuration.

Currently this does not work as GLOBAL git configuration file is used.

What did you expect to see?

It would be great if the existence of project's gitconfig is checked first and used in that case. Otherwise fall back to global configuration.

What did you see instead?

Opposite behavior.

[bradfitz]

/cc @bcmills

[bcmills]

Duplicate of #31256