Non-working windows10+vim+hyper+git bash setup

.hyper.js

module.exports = {
  config: {
    // default font size in pixels for all tabs
    fontSize: 18,
    fontFamily: '"Inconsolata for Powerline Medium", "Comic Sans MS", monospace',
    cursorColor: 'rgba(248,28,229,0.8)',
    cursorShape: 'BLOCK',
    padding: '12px 14px',

    shell: 'C:\\Program Files\\Git\\git-cmd.exe',
    shellArgs: ['--command=usr/bin/bash.exe', '-l', '-i'],
    env: {
      "TERM": "cygwin",
    },
    copyOnSelect: true,
    bellSoundURL: 'http://soundbible.com/grab.php?id=605&type=mp3',
  },
  plugins: [
    //'hyper-solarized-light', // no difference
    //'hyperlinks',
  ],
  localPlugins: []
};

_vimrc

" Workaround for: https://github.com/VundleVim/Vundle.vim/issues/779
" and https://github.com/junegunn/vim-plug/issues/539
let &shell='cmd.exe'

call plug#begin('/c/Users/there/vimfiles/plugged')
  Plug 'fatih/vim-go', { 'do': ':GoInstallBinaries' }
  Plug 'maralla/completor.vim'
  "Plug 'nsf/gocode', { 'rtp': 'vim', 'do': '$VIM/plugged/gocode/vim/symlink.sh' } " makes no difference
call plug#end()
let g:completor_gocode_binary = '/c/Users/there/go/bin/gocode'
inoremap <expr> <Tab> pumvisible() ? "\<C-n>" : "\<Tab>"
inoremap <expr> <S-Tab> pumvisible() ? "\<C-p>" : "\<S-Tab>"
inoremap <expr> <cr> pumvisible() ? "\<C-y>\<cr>" : "\<cr>"

symptoms.md

Expected behavior: autocompletion works while editing go files in CLI vim, from git bash in hyper term on windows 10

Actual behavior: Completion popup does not occur when editing files :PlugInstall reports success but the ~/vimfiles/plugged directory is empty Vim-go's :GoAddTags works fine gocode binary behaves differently in the two terms:

In hyper:

$ gocode

$ echo $?
130

$ gocode set

$ echo $?
0

$ gocode set | wc
      9      18     185

In git bash's mingw term:

$ gocode

$ echo $?
0
$ gocode set
propose-builtins false
lib-path ""
custom-pkg-prefix ""
custom-vendor-dir ""
autobuild false
force-debug-output ""
package-lookup-mode "go"
close-timeout 1800
unimported-packages false

$ echo $?
0