import "github.com/pravj/geo_pattern/pattern"

will import from the file system, at $GOPATH/src/github.com/pravj/geo_pattern/pattern/

however, go get will fetch from the URL and install it in said path (it's a mixed blessing)

The [free] Little Go Book [1] makes a special note of it :)

[1] http://openmymind.net/assets/go/go.pdf