Golang relative package import after renaming

My $GOPATH is

"/Users/peter/goworkspace"

My current golang version:

go version go1.6 darwin/amd64

I have multiple golang projects under this workspace, so here is the the structure of directories

+/goworkspace  
  +---/bin  
  +---/pkg  
  +---/src  
    +---/project1
        +---package1 
           +---file1.go 
           +---file2.go 
           +---file3.go 
        +---package2 
        +---package3 
        +---main.go 
    +---/project2
    +---/project3

In my proj1's main.go, I will use the imports from other packages under this project, it will look like:

import(  
     "./package1"      
     "./package2"      
     "./package3"
 )  

however when I run "go build",I'm keeping getting error saying:
"
can't load package: local import "../package" in non-local package

If I prefer not to use relative package path, for example use it like:

import(
    "project1/package1"  
    "project1/package2"   
    "project1/package3"   
)  

then everything will work.

What is wrong with my code if I use the relative package path?
And what is the best practice for package import if the project1's name will change in the future, for example it is changed to projecet1v2?
Do I need to manually update the imported package's name then?

Rule #1: Don't use relative imports. This is (partly) why you're running into issues. Read through this: https://golang.org/doc/code.html#Library

Use the fully qualified import paths (as you showed):

import(
    "project1/package1"  
    "project1/package2"   
    "project1/package3"
    // Or ideally, so others can access it in the future:
    "github.com/<yourusername>/project1/package4"
)  

If for some reason you want to version your package, you can either:

• Provide a new repository (import URL)
• Use a service like gopkg.in (http://labix.org/gopkg.in) to provide versioned import URLs (e.g. gopkg.in/you/pkgname.v2)