PR#3576: kojivmd: improve topurl example and error handling

Merges #3576
https://pagure.io/koji/pull-request/3576

vm/kojivmd

@@ -715,6 +715,7 @@ class VMExecTask(BaseTaskHandler):
             koji.ensuredir(os.path.dirname(localpath))
             # closing needs to be used for requests < 2.18.0
             with closing(requests.get(remote_url, stream=True)) as response:
+                response.raise_for_status()
                 with open(localpath, 'wb') as f:
                     for chunk in response.iter_content(chunk_size=65536):
                         f.write(chunk)

vm/kojivmd.conf

@@ -15,7 +15,7 @@
 ; workdir=/tmp/koji
 
 ; The url where the Koji root directory (/mnt/koji) can be accessed
-topurl=http://koji.example.com/kojiroot
+topurl=http://koji.example.com/kojifiles
 
 ; The URL for the xmlrpc server
 server=http://hub.example.com/kojihub