ID 337218 - Nuke Studio returns an error when the Nuke <> Mari Bridge is loaded

Problem summary
Nuke Studio 11.1 returns an error when the Nuke <> Mari Bridge is loaded

Customer reported version
4.0v2
Customer reported platform
centos7

Steps to reproduce

1) Set up the Nuke <> Mari Bridge by copying the relevant files from /Media/Scripts/Nuke to the .nuke folder, or by adding the Mari Bridge location to the nuke plugin paths using nuke.pluginAddPath() in the init.py file.

Further steps can be found here:

Q100203: Nuke <> Mari Bridge Connection Setup

Q100184: How to install the Nuke <> Mari bridge.

2) Launch Mari

3) Launch Nuke Studio 11.1v1 or Nuke Studio 11.1v2

4) Notice that the following error appears in Nuke Studio's Script Editor:

Traceback (most recent call last):
File "/swiss/tool/nuke-versions/11.1v2/plugins/nuke/callbacks.py", line 72, in onCreate
_doCallbacks(onCreates)
File "/swiss/tool/nuke-versions/11.1v2/plugins/nuke/callbacks.py", line 46, in _doCallbacks
f[0](f[1],*f[2])
File "/swiss/tool/mari-versions/Mari4.0v2/Media/Scripts/Nuke/mari_bridge.py", line 1440, in _rootKnobCreated
loadDefaults()
File "/swiss/tool/mari-versions/Mari4.0v2/Media/Scripts/Nuke/mari_bridge.py", line 1533, in loadDefaults
if not root[knob].value():
NameError: knob socketPort does not exist

5) In the Script Editor, run the following script:

import telnetlib
tn = telnetlib.Telnet("localhost", 6100)
tn.write("print 'I AM A MARI TEST'\n")
tn.write("\x04")

6) Mari will return 'I AM A MARI TEST' in the Python Console showing that the connection is still valid.
Workaround
You should be able to use the Nuke <> Mari bridge as expected but the error will occur

Reproduced by support
Affects all versions of Mari paired with Nuke Studio 11.1v1 and 11.1v2

Error does not occur in:
Nuke 11.1v2
Nuke 11.1v1
Nuke Studio 11.0v4

Expected behaviour
As in Nuke and in earlier versions of Nuke Studio, no error should appear in the Script Editor

Actual behaviour
Nuke Studio 11.1 displays a traceback error when the Nuke <> Mari Bridge is installed

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