semver may fail with large concurrency

https://github.com/jonathanong/component-process.js/issues/11

should resolve component-process#11, but it doesn't when semver's concurrency is > 2 or something.

for some reason, the callback for resolving `component/query` isn't called...

note that this isn't really important. for now, installation speeds will be less than ideal, but that can be mitigated by pinning!
