message: Properly copy in `yarn.lock` from the app
diff: @@ -90,7 +90,7 @@ function dockerfile(packages, appName) {
  for (let pack of packages) {
  let dir = `packages/${pack.name}/`; // Don't use path.join, in case host is Windows
  let json = dir+'package.json';
  - let yarn = dir+'yarn.lock?'; // COPY errors out if a directly specified file is missing, but is ok with a pattern matching 0 files
  + let yarn = dir+'yarn.loc[k]'; // COPY errors out if a directly specified file is missing, but is ok with a pattern matching 0 files
  let files = JSON.stringify([json, yarn, dir]);
  file.push(`COPY ${files}`);
  }
  