octoprint maintenance branch startup error

2018-04-24 21:39:26,641 - octoprint.startup - INFO - ******************************************************************************
2018-04-24 21:39:26,643 - octoprint.startup - INFO - Starting OctoPrint 1.3.9.dev125+g81626ce
2018-04-24 21:39:26,643 - octoprint.startup - INFO - ******************************************************************************
2018-04-24 21:39:26,702 - octoprint.util.connectivity_checker - INFO - Connectivity changed from offline to online
2018-04-24 21:39:26,707 - octoprint.startup - INFO - Blacklist processing done
2018-04-24 21:39:26,755 - octoprint.plugin.core - INFO - Loading plugins from /home/pi/oprint/lib/python2.7/site-packages/OctoPrint-1.3.9.dev125_g81626ce-py2.7.egg/octoprint/plugins, /home/pi/.octoprint/plugins and installed plugin packages...
2018-04-24 21:39:27,148 - octoprint.plugin.core - INFO - Plugin CuraEngine (<= 15.04) is disabled.
2018-04-24 21:39:28,231 - octoprint.plugin.core - INFO - Plugin Virtual Printer is disabled.
2018-04-24 21:39:28,651 - octoprint.plugin.core - INFO - Found 14 plugin(s) providing 12 mixin implementations, 9 hook handlers
2018-04-24 21:39:28,760 - octoprint.server.heartbeat - INFO - Starting server heartbeat, 900.0s interval
2018-04-24 21:39:28,789 - octoprint.server - INFO - Intermediary server started
2018-04-24 21:39:28,790 - octoprint.plugin.core - INFO - Loading plugins from /home/pi/oprint/lib/python2.7/site-packages/OctoPrint-1.3.9.dev125_g81626ce-py2.7.egg/octoprint/plugins, /home/pi/.octoprint/plugins and installed plugin packages...
2018-04-24 21:39:29,112 - octoprint.plugin.core - INFO - Found 14 plugin(s) providing 12 mixin implementations, 9 hook handlers
2018-04-24 21:39:29,148 - octoprint.filemanager.storage - INFO - Initializing the file metadata for /home/pi/.octoprint/uploads...
2018-04-24 21:39:32,001 - octoprint.filemanager.storage - INFO - ... file metadata for /home/pi/.octoprint/uploads initialized successfully.
2018-04-24 21:39:32,077 - octoprint.plugins.softwareupdate - INFO - Version cache was created for another version of OctoPrint, not using it
2018-04-24 21:39:34,541 - octoprint.util.pip - INFO - Using "/home/pi/oprint/bin/python -m pip" as command to invoke pip
2018-04-24 21:39:36,945 - octoprint.util.pip - INFO - Version of pip is 9.0.1
2018-04-24 21:39:36,946 - octoprint.util.pip - INFO - pip installs to /home/pi/oprint/lib/python2.7/site-packages (writable -> yes), --user flag needed -> no, virtual env -> yes
2018-04-24 21:39:36,946 - octoprint.util.pip - INFO - ==> pip ok -> yes
2018-04-24 21:39:36,954 - octoprint.plugin.core - INFO - Initialized 12 plugin implementation(s)
2018-04-24 21:39:36,963 - octoprint.plugin.core - INFO - 14 plugin(s) registered with the system:
|  Announcement Plugin (bundled) = /home/pi/oprint/lib/python2.7/site-packages/OctoPrint-1.3.9.dev125_g81626ce-py2.7.egg/octoprint/plugins/announcements
|  Core Wizard (bundled) = /home/pi/oprint/lib/python2.7/site-packages/OctoPrint-1.3.9.dev125_g81626ce-py2.7.egg/octoprint/plugins/corewizard
| !CuraEngine (<= 15.04) (bundled) = /home/pi/oprint/lib/python2.7/site-packages/OctoPrint-1.3.9.dev125_g81626ce-py2.7.egg/octoprint/plugins/cura
|  Discovery (bundled) = /home/pi/oprint/lib/python2.7/site-packages/OctoPrint-1.3.9.dev125_g81626ce-py2.7.egg/octoprint/plugins/discovery
|  Logging (bundled) = /home/pi/oprint/lib/python2.7/site-packages/OctoPrint-1.3.9.dev125_g81626ce-py2.7.egg/octoprint/plugins/logging
|  Material Settings (0.1.0) = /home/pi/Octoprint-Material-Settings/octoprint_material_settings
|  Navbar Temperature Plugin (0.9) = /home/pi/oprint/local/lib/python2.7/site-packages/octoprint_navbartemp
|  OctoPi Support Plugin (bundled) = /home/pi/oprint/lib/python2.7/site-packages/OctoPrint-1.3.9.dev125_g81626ce-py2.7.egg/octoprint/plugins/octopi_support
|  Plugin Manager (bundled) = /home/pi/oprint/lib/python2.7/site-packages/OctoPrint-1.3.9.dev125_g81626ce-py2.7.egg/octoprint/plugins/pluginmanager
|  Print Queue (0.1.0) = /home/pi/Octoprint-Print-Queue/octoprint_print_queue
|  Printer Safety Check (bundled) = /home/pi/oprint/lib/python2.7/site-packages/OctoPrint-1.3.9.dev125_g81626ce-py2.7.egg/octoprint/plugins/printer_safety_check
|  Software Update (bundled) = /home/pi/oprint/lib/python2.7/site-packages/OctoPrint-1.3.9.dev125_g81626ce-py2.7.egg/octoprint/plugins/softwareupdate
|  TouchUI (0.3.11) = /home/pi/oprint/local/lib/python2.7/site-packages/octoprint_touchui
| !Virtual Printer (bundled) = /home/pi/oprint/lib/python2.7/site-packages/OctoPrint-1.3.9.dev125_g81626ce-py2.7.egg/octoprint/plugins/virtual_printer
2018-04-24 21:39:36,979 - octoprint.environment - INFO - Detected environment is Python 2.7.9 under Linux (linux2). Details:
|  hardware:
|    cores: 4
|    freq: 1200.0
|    ram: 901685248
|  os:
|    id: linux
|    platform: linux2
|  plugins:
|    octopi_support:
|      model: 3B
|      revision: a22082
|      version: 0.14.0
|  python:
|    pip: 9.0.1
|    version: 2.7.9
|    virtualenv: /home/pi/oprint
2018-04-24 21:39:36,989 - octoprint.server - INFO - Reset webasset folder /home/pi/.octoprint/generated/webassets...
2018-04-24 21:39:37,013 - octoprint.server - INFO - Reset webasset folder /home/pi/.octoprint/generated/.webassets-cache...
2018-04-24 21:39:37,156 - octoprint.cli.server - ERROR - Uncaught exception
Traceback (most recent call last):
  File "/home/pi/oprint/bin/octoprint", line 9, in <module>
    load_entry_point('OctoPrint==1.3.9.dev125-g81626ce', 'console_scripts', 'octoprint')()
  File "/home/pi/oprint/local/lib/python2.7/site-packages/OctoPrint-1.3.9.dev125_g81626ce-py2.7.egg/octoprint/__init__.py", line 565, in main
    octo(args=args, prog_name="octoprint", auto_envvar_prefix="OCTOPRINT")
  File "/home/pi/oprint/local/lib/python2.7/site-packages/click-6.2-py2.7.egg/click/core.py", line 716, in __call__
    return self.main(*args, **kwargs)
  File "/home/pi/oprint/local/lib/python2.7/site-packages/click-6.2-py2.7.egg/click/core.py", line 696, in main
    rv = self.invoke(ctx)
  File "/home/pi/oprint/local/lib/python2.7/site-packages/click-6.2-py2.7.egg/click/core.py", line 1060, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "/home/pi/oprint/local/lib/python2.7/site-packages/click-6.2-py2.7.egg/click/core.py", line 889, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/home/pi/oprint/local/lib/python2.7/site-packages/click-6.2-py2.7.egg/click/core.py", line 534, in invoke
    return callback(*args, **kwargs)
  File "/home/pi/oprint/local/lib/python2.7/site-packages/click-6.2-py2.7.egg/click/decorators.py", line 17, in new_func
    return f(get_current_context(), *args, **kwargs)
  File "/home/pi/oprint/local/lib/python2.7/site-packages/OctoPrint-1.3.9.dev125_g81626ce-py2.7.egg/octoprint/cli/server.py", line 183, in serve_command
    ignore_blacklist)
  File "/home/pi/oprint/local/lib/python2.7/site-packages/OctoPrint-1.3.9.dev125_g81626ce-py2.7.egg/octoprint/cli/server.py", line 104, in run_server
    octoprint_server.run()
  File "/home/pi/oprint/local/lib/python2.7/site-packages/OctoPrint-1.3.9.dev125_g81626ce-py2.7.egg/octoprint/server/__init__.py", line 496, in run
    session_kls=util.sockjs.ThreadSafeSession)
  File "/home/pi/oprint/local/lib/python2.7/site-packages/OctoPrint-1.3.9.dev125_g81626ce-py2.7.egg/octoprint/vendor/sockjs/tornado/router.py", line 111, in __init__
    self.io_loop)
TypeError: __init__() takes exactly 3 arguments (4 given)

Hm... That's odd, Tornado 4.5.3 definitely should allow for 4 arguments there and this is what current maintenance branch at that checkout should depend on. I also can't reproduce this.

What does ~/oprint/bin/pip freeze | grep -i tornado output?