Non-blocking Jenkins hooks
Hi lovely sysadmins! Today a 'git push' of mine hung for quite a while on a jenkins hook which eventually failed...
```
remote: create mode 100644 test/unit/descriptor/data/collector/index.py
remote: create mode 100644 test/unit/descriptor/data/collector/microdescs-2019-05-cropped.tar
remote: create mode 100644 test/unit/descriptor/data/collector/server-descriptors-2005-12-cropped.tar
remote: create mode 100644 test/unit/descriptor/data/compressed_bz2
remote: == xx-jenkins-trigger ==
remote: [hook[10397]] Triggering jenkins build for (https://git.torproject.org/stem.git, master, 97c9a58eab40ce32256afbb02a4f8c6c84045bb1).
remote: <!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">
remote: <html><head>
remote: <title>502 Proxy Error</title>
remote: </head><body>
remote: <h1>Proxy Error</h1>
remote: <p>The proxy server received an invalid
remote: response from an upstream server.<br />
remote: The proxy server could not handle the request <em><a href="/git/notifyCommit">GET /git/notifyCommit</a></em>.<p>
remote: Reason: <strong>Error reading from remote server</strong></p></p>
remote: <hr>
remote: <address>Apache Server at jenkins.torproject.org Port 443</address>
remote: </body></html>
remote: [hook[10397]] Jenkins triggers done.
To ssh://torgit/stem.git
4357e54..97c9a58 master -> master
```
Is there a reason this hook cannot be a post-push background process? It seems like a mistake for it to cause developer pushes to hang.
Thanks!
issue