I see somewhat frequent "step interrupted"s on
https://build.chromium.org/p/tryserver.chromium.win/builders/win_clang_x64_dbg/
with stacks looking e.g. like so:

Traceback (most recent call last):
File
"/home/chrome-bot/buildbot/build/third_party/twisted_10_2/twisted/spread/pb.py",
line 516, in expressionReceived
method(*sexp[1:])
File
"/home/chrome-bot/buildbot/build/third_party/twisted_10_2/twisted/spread/pb.py",
line 828, in proto_message
self._recvMessage(self.localObjectForID, requestID, objectID, message,
answerRequired, netArgs, netKw)
File
"/home/chrome-bot/buildbot/build/third_party/twisted_10_2/twisted/spread/pb.py",
line 842, in _recvMessage
netResult = object.remoteMessageReceived(self, message, netArgs, netKw)
File
"/home/chrome-bot/buildbot/build/third_party/twisted_10_2/twisted/spread/flavors.py",
line 114, in remoteMessageReceived
state = method(*args, **kw)
--- <exception caught here> ---
File
"/home/chrome-bot/buildbot/build/third_party/buildbot_8_4p1/buildbot/process/buildstep.py",
line 176, in remote_update
self.remoteUpdate(update)
File
"/home/chrome-bot/buildbot/build/third_party/buildbot_8_4p1/buildbot/process/metrics.py",
line 81, in wrapper
return func(*args, **kwargs)
File
"/home/chrome-bot/buildbot/build/third_party/buildbot_8_4p1/buildbot/process/buildstep.py",
line 362, in remoteUpdate
self.addStdout(update['stdout'])
File
"/home/chrome-bot/buildbot/build/third_party/buildbot_8_4p1/buildbot/process/buildstep.py",
line 333, in addStdout
self.logs['stdio'].addStdout(data)
File
"/home/chrome-bot/buildbot/build/third_party/buildbot_8_4p1/buildbot/status/logfile.py",
line 458, in addStdout
self.addEntry(STDOUT, text)
File
"/home/chrome-bot/buildbot/build/third_party/buildbot_8_4p1/buildbot/status/logfile.py",
line 454, in addEntry
w.logChunk(build, step, self, channel, text)
File "/home/chrome-bot/buildbot/build/scripts/master/chromium_step.py", line
868, in logChunk
self.outReceived(line)
File "/home/chrome-bot/buildbot/build/scripts/master/chromium_step.py", line
878, in outReceived
self.cursor['log'].addStdout(data)
File
"/home/chrome-bot/buildbot/build/third_party/buildbot_8_4p1/buildbot/status/logfile.py",
line 458, in addStdout
self.addEntry(STDOUT, text)
File
"/home/chrome-bot/buildbot/build/third_party/buildbot_8_4p1/buildbot/status/logfile.py",
line 414, in addEntry
assert not self.finished
exceptions.AssertionError: 


There are different examples:

https://build.chromium.org/p/tryserver.chromium.win/builders/win_clang_x64_dbg/builds/280/steps/steps/logs/err.text
https://build.chromium.org/p/tryserver.chromium.win/builders/win_clang_x64_dbg/builds/349/steps/steps/logs/err.text
https://build.chromium.org/p/tryserver.chromium.win/builders/win_clang_x64_dbg/builds/351/steps/steps/logs/err.text
https://build.chromium.org/p/tryserver.chromium.win/builders/win_clang_x64_dbg/builds/393