Autocompletion doesn't work for packages which were imported before saving the file

[nezorflame]

Continuing the discussion started in #1944 and #2164 in a new issue.

With "go.toolsEnvVars": { "GO111MODULE": "on" }, gocode-gomod is being launched now, which is good.
But, it still fails to give suggestions to the package functions before you save the file.

Prerequisits
Ext. version: 0.7.1-beta.5
OS: macOS 10.14.1
Latest vscode, Go 1.11.2, all Go tools updated through vscode-go.
Create simple main.go with empty main(), enable modules by go mod init.

Steps to reproduce:

1. Action: Start writing fm
   Expect: fmt package should be suggested to be imported
   Result: success - got the suggestion:

2. Action: Import fmt, write . to have function suggestions
   Expect: fmt package functions should be suggested
   Result: failure - nothing happens:

gocode-gomod -s -debug output (doubled for some reason?..):

2018/12/07 16:41:00 Got autocompletion request for '/Users/nezorflame/Go/src/test-project/main.go'
2018/12/07 16:41:00 Cursor at: 52
2018/12/07 16:41:00 -------------------------------------------------------
package main

import (
        "fmt"
)

func main() {
        fmt.#
}
2018/12/07 16:41:00 -------------------------------------------------------
2018/12/07 16:41:00 error in package test-project: /Users/nezorflame/Go/src/test-project/main.go:4:2:could not import fmt (no metadata for fmt)
2018/12/07 16:41:00 Elapsed duration: 103.788631ms
2018/12/07 16:41:00 Offset: 0
2018/12/07 16:41:00 Number of candidates found: 0
2018/12/07 16:41:00 Candidates are:
2018/12/07 16:41:00 =======================================================
2018/12/07 16:41:00 Got autocompletion request for '/Users/nezorflame/Go/src/test-project/main.go'
2018/12/07 16:41:00 Cursor at: 65
2018/12/07 16:41:00 -------------------------------------------------------
package main
import "fmt"

import (
        "fmt"
)

func main() {
        fmt.#
}
2018/12/07 16:41:00 -------------------------------------------------------
2018/12/07 16:41:00 error in package test-project: /Users/nezorflame/Go/src/test-project/main.go:2:8:could not import fmt (no metadata for fmt)
2018/12/07 16:41:00 error in package test-project: /Users/nezorflame/Go/src/test-project/main.go:5:2:fmt redeclared in this block
2018/12/07 16:41:00 error in package test-project: /Users/nezorflame/Go/src/test-project/main.go:2:8:    other declaration of fmt
2018/12/07 16:41:00 Elapsed duration: 98.44108ms
2018/12/07 16:41:00 Offset: 0
2018/12/07 16:41:00 Number of candidates found: 0
2018/12/07 16:41:00 Candidates are:
2018/12/07 16:41:00 =======================================================

But, if you save the file and try again, it will work this time!

3. Action: Save the file, delete the . and insert it again:
   Expect: fmt package functions should be suggested
   Result: success - got the functions now:

[ramya-rao-a]

This is being tracked upstream in http://github.com/stamblerre/gocode/issues/3

[ramya-rao-a]

@nezorflame The fix for this has been pushed in the upstream. Can you run the command Go: Install/Update Tools, choose gocode-gomod, press Ok to update it and try again?

[nezorflame]

Yes, it works. Great job @stamblerre!