from spinnaker/kork#1098 to fix
```
java.lang.AssertionError:
Expecting throwable message:
"Status: 500, URL: http://localhost:41703/-/healthy, Message: Internal Server Error"
to contain:
"500 Internal Server Error"
but did not.
Throwable that failed the check:
com.netflix.spinnaker.kork.retrofit.exceptions.SpinnakerHttpException: Status: 500, URL: http://localhost:41703/-/healthy, Message: Internal Server Error
at com.netflix.spinnaker.kork.retrofit.exceptions.SpinnakerRetrofitErrorHandler.handleError(SpinnakerRetrofitErrorHandler.java:55)
at retrofit.RestAdapter$RestHandler.invoke(RestAdapter.java:242)
at com.sun.proxy.$Proxy71.isHealthy(Unknown Source)
at com.netflix.kayenta.prometheus.service.PrometheusRemoteServiceTest.lambda$isHealthyReturnsInternalServerError$0(PrometheusRemoteServiceTest.java:88)
at org.assertj.core.api.ThrowableAssert.catchThrowable(ThrowableAssert.java:62)
at org.assertj.core.api.AssertionsForClassTypes.catchThrowable(AssertionsForClassTypes.java:877)
at org.assertj.core.api.Assertions.catchThrowable(Assertions.java:1306)
at org.assertj.core.api.Assertions.assertThatThrownBy(Assertions.java:1178)
at com.netflix.kayenta.prometheus.service.PrometheusRemoteServiceTest.isHealthyReturnsInternalServerError(PrometheusRemoteServiceTest.java:88)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:566)
at org.junit.platform.commons.util.ReflectionUtils.invokeMethod(ReflectionUtils.java:688)
...
Caused by: retrofit.RetrofitError: 500 Internal Server Error
at retrofit.RetrofitError.httpError(RetrofitError.java:40)
at retrofit.RestAdapter$RestHandler.invokeRequest(RestAdapter.java:388)
at retrofit.RestAdapter$RestHandler.invoke(RestAdapter.java:240)
... 90 more
at com.netflix.kayenta.prometheus.service.PrometheusRemoteServiceTest.isHealthyReturnsInternalServerError(PrometheusRemoteServiceTest.java:91)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:566)
at org.junit.platform.commons.util.ReflectionUtils.invokeMethod(ReflectionUtils.java:688)
...
```