Cannot create a proper vsix from the master branch

Doing:

npm update gulp

on a local clone of the extension generates a vsix file with missing node_modules:

listing the contents of the archive gives out.1.txt

whether the original vsix gives out.2.txt

My node & npm versions:

λ npm version
npm info it worked if it ends with ok
npm info using npm@2.15.1
npm info using node@v4.4.4
npm info ok
npm info it worked if it ends with ok
npm info using npm@3.9.5
npm info using node@v4.4.4
{ npm: '3.9.5',
  ares: '1.10.1-DEV',
  http_parser: '2.5.2',
  icu: '56.1',
  modules: '46',
  node: '4.4.4',
  openssl: '1.0.2h',
  uv: '1.8.0',
  v8: '4.5.103.35',
  zlib: '1.2.8' }
npm info ok

microsoft / vsts-nexus

Cannot create a proper vsix from the master branch #6