gitlab-runner sometimes ignores jobs
### Summary
I am having an intermittent issue where a private runner will not pick up a job. Retrying the job will usually kick it off.
### Steps to reproduce
Start runner in debug.
```
gitlab-runner --debug run --config /etc/gitlab-runner/config.toml
```
Watch the output until you see the following.
```
Checking for jobs... nothing runner=xxxxxxx
Feeding runners to channel builds=0
```
Hit `Create Pipeline` button immiediatly after seeing the above log message.
Watch the log to see that the jobs are checked but not picked up.
```
Checking for jobs... nothing runner=xxxxxxxx
Feeding runners to channel builds=0
Checking for jobs... nothing runner=xxxxxxxx
Feeding runners to channel builds=0
Checking for jobs... nothing runner=xxxxxxxx
Feeding runners to channel builds=0
```
The job is never picked up and stays in the pending state. I have waited more the 45 minutes for it to resolve.
Restarting the runner will cause the job to be picked up. You can also do the following: Open the edit page for the runner. Don't edit the tags but remove a space so there is a difference to save. Save the runner. The jobs is instantly picked up by the runner.
### Example Project
https://gitlab.com/jrob007/test
### What is the current *bug* behavior?
The job sits in the pending state.
### What is the expected *correct* behavior?
The job is picked up by the runner.
### Relevant logs and/or screenshots
Gitlab runner version
```
Version: 10.7.0
Git revision: 7c273476
Git branch: 10-7-stable
GO version: go1.8.7
Built: 2018-04-22T13:43:35+00:00
OS/Arch: linux/amd64
```
```toml
concurrent = 1
check_interval = 0
[[runners]]
name = "docker-runer-linux-development"
url = "https://gitlab.com/"
token = "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"
executor = "docker"
environment = ["HTTPS_PROXY=http://xxxxxxxxxxxxxxxxxxxxxx:1234", "HTTP_PROXY=http://xxxxxxxxxxxxxxxxxxxxxx:1234"]
pre_clone_script = "git config --global http.proxy $HTTP_PROXY; git config --global https.proxy $HTTPS_PROXY"
[runners.docker]
tls_verify = false
image = "node:latest"
privileged = false
disable_cache = false
volumes = ["/cache"]
shm_size = 0
[runners.cache]
```
### Output of checks
This bug happens on GitLab.com
### Other relevant information
* Running behind a proxy.
### Things I have tried
* Waiting.
* Saving the runner with tags in a different order.
* Checking `Run untagged jobs`.
Potential workaround
* Specifying only the required tags on the runner. Removed tags that were not relevant.
issue