Fix flaky test suite by avoiding concurrent requests
Fix flaky test suite by avoiding concurrent requests

Avoid concurrent HTTP requests to the registry. Since `readable.push()`
can lead to a subsequent call to `_read()`, a new request could
previously have been dispatched while processing the current one.

If the new request returned an empty result, that sometimes ended the
stream before the original first request was fully processed.

Fix that by tracking whether a request is currently active.

chrisdickinson/npm-get-dependents