https://launchpad.net/~ubuntu-toolchain-r/+archive/ubuntu/test/+build/8146556 finished its first (long) build successfully, but failed to fetch one of the files, and so gave up. The buildd-manager logs look like this (in part):
2015-10-21 11:26:17+0000 [QueryProtocol,client] Processing finished job PACKAGEBUILD-8146556 (amd64 build of gcc-5 5.2.1-22ubuntu3 in ubuntu wily RELEASE) from builder lgw01-08: OK
2015-10-21 11:26:17+0000 [QueryProtocol,client] Starting factory <HTTPDownloader: http://lgw01-08.lgw01.scalingstack.ppa:8221/filecache/buildlog>
2015-10-21 11:26:38+0000 [HTTPPageDownloader,client] Starting factory <HTTPDownloader: http://lgw01-08.lgw01.scalingstack.ppa:8221/filecache/ec59fc8f5c9d513b9085a8f10a03bafff8620d94>
2015-10-21 11:26:38+0000 [HTTPPageDownloader,client] Starting factory <HTTPDownloader: http://lgw01-08.lgw01.scalingstack.ppa:8221/filecache/3bb4f03001411c9baa5b946e725d2e63c6be9d45>
[lots more of the same]
2015-10-21 11:26:39+0000 [HTTPPageDownloader,client] Stopping factory <HTTPDownloader: http://lgw01-08.lgw01.scalingstack.ppa:8221/filecache/buildlog>
2015-10-21 11:26:56+0000 [HTTPPageDownloader,client] Stopping factory <HTTPDownloader: http://lgw01-08.lgw01.scalingstack.ppa:8221/filecache/856260abfec2057543c972b64ef339f3f6e9cbb1>
2015-10-21 11:26:56+0000 [HTTPPageDownloader,client] Stopping factory <HTTPDownloader: http://lgw01-08.lgw01.scalingstack.ppa:8221/filecache/33805f15f6e46828ef920975be356a038edb966d>
[lots more of the same]
2015-10-21 11:26:58+0000 [HTTPPageDownloader,client] Scanning lgw01-08 failed with: FirstError[#62, [Failure instance: Traceback (failure with no frames): <class 'twisted.internet.error.ConnectionLost'>: Connection to the other side was lost in a non-clean fashion.
2015-10-21 11:26:58+0000 [HTTPPageDownloader,client] ]]
2015-10-21 11:26:58+0000 [HTTPPageDownloader,client] Traceback (most recent call last):
2015-10-21 11:26:58+0000 [HTTPPageDownloader,client] Failure: twisted.internet.defer.FirstError: FirstError[#62, [Failure instance: Traceback (failure with no frames): <class 'twisted.internet.error.ConnectionLost'>: Connection to the other side was lost in a non-clean fashion.
2015-10-21 11:26:58+0000 [HTTPPageDownloader,client] ]]
2015-10-21 11:26:58+0000 [HTTPPageDownloader,client]
2015-10-21 11:26:58+0000 [HTTPPageDownloader,client] Judged builder lgw01-08 (3 failures) with job PACKAGEBUILD-8146556 (3 failures): None, True
2015-10-21 11:26:58+0000 [HTTPPageDownloader,client] Requeueing job PACKAGEBUILD-8146556.
This looks like a temporary glitch that might well have been fixed if only we'd tried a couple more times. I think BuilderSlave.getFile could do with some retry logic.
We retry the scan three times, it just happened that in this case there were two widespread network issues earlier in the build that caused the failure here to be fatal. We could implement extra retry logic for each download, but I'm not sure it's worth it.
2015-10-21 03:31:16+0000 [-] Scanning lgw01-08 failed with:
2015-10-21 03:31:49+0000 [Uninitialized] Scanning lgw01-08 failed with: An error occurred while connecting: 113: No route to host.