feat(git): support packages in a subdirectory

Author: sspiff

lib/fetchers/git.js

@@ -74,7 +74,8 @@ Fetcher.impl(fetchGit, {
             if (streamError) { throw streamError }
             manifest._resolved = spec.saveSpec.replace(/(:?#.*)?$/, `#${HEAD}`)
             manifest._uniqueResolved = manifest._resolved
-            return packDir(manifest, manifest._uniqueResolved, tmp, stream, opts)
+            const dir = `${tmp}${spec.gitSubdir || ''}`
+            return packDir(manifest, manifest._uniqueResolved, dir, stream, opts)
           })
         }).catch(err => stream.emit('error', err))
       }