```
$ gvt delete golang.org/x/net/context
$ gvt fetch golang.org/x/net/context
2017/10/08 XX:XX:XX Fetching: golang.org/x/net/context
$ git grep -l "golang.org/x/net/context" | grep -v vendor | xargs sed -i 's:golang.org/x/net/context:context:g'
$ git grep -l "context/ctxhttp" | grep -v vendor | xargs sed -i 's:context/ctxhttp:golang.org/x/net/context/ctxhttp:g'
$ gofmt -s -w app
$ gofmt -s -w common
$ gofmt -s -w probe
$ gofmt -s -w prog
$ gofmt -s -w tools
```

This fixes errors like:
```
app/multitenant/aws_collector.go:222: cannot use func literal (type func("github.com/weaveworks/scope/vendor/golang.org/x/net/context".Context) error) as type func("context".Context) error in argument to instrument.TimeRequestHistogram
app/multitenant/aws_collector.go:439: cannot use func literal (type func("github.com/weaveworks/scope/vendor/golang.org/x/net/context".Context) error) as type func("context".Context) error in argument to instrument.TimeRequestHistogram
app/multitenant/memcache_client.go:155: cannot use func literal (type func("github.com/weaveworks/scope/vendor/golang.org/x/net/context".Context) error) as type func("context".Context) error in argument to instrument.TimeRequestHistogramStatus
app/multitenant/memcache_client.go:210: cannot use func literal (type func("github.com/weaveworks/scope/vendor/golang.org/x/net/context".Context) error) as type func("context".Context) error in argument to instrument.TimeRequestHistogramStatus
app/multitenant/s3_client.go:74: cannot use func literal (type func("github.com/weaveworks/scope/vendor/golang.org/x/net/context".Context) error) as type func("context".Context) error in argument to instrument.TimeRequestHistogram
app/multitenant/s3_client.go:91: cannot use func literal (type func("github.com/weaveworks/scope/vendor/golang.org/x/net/context".Context) error) as type func("context".Context) error in argument to instrument.TimeRequestHistogram
app/multitenant/sqs_control_router.go:99: cannot use func literal (type func("github.com/weaveworks/scope/vendor/golang.org/x/net/context".Context) error) as type func("context".Context) error in argument to instrument.TimeRequestHistogram
app/multitenant/sqs_control_router.go:133: cannot use func literal (type func("github.com/weaveworks/scope/vendor/golang.org/x/net/context".Context) error) as type func("context".Context) error in argument to instrument.TimeRequestHistogram
app/multitenant/sqs_control_router.go:163: cannot use func literal (type func("github.com/weaveworks/scope/vendor/golang.org/x/net/context".Context) error) as type func("context".Context) error in argument to instrument.TimeRequestHistogram
app/multitenant/sqs_control_router.go:199: cannot use func literal (type func("github.com/weaveworks/scope/vendor/golang.org/x/net/context".Context) error) as type func("context".Context) error in argument to instrument.TimeRequestHistogram
app/multitenant/sqs_control_router.go:199: too many errors
```