QGIS » QGIS Application

Steps to reproduce:

0. Have a Windows user account that contains unicode characters (e.g. user "José Fußball").
1. Create a plugin with just the following code:

class UnicodeDebug:
    def __init__(self, iface):
        iface.mapCanvas().mapRenderer()

    def initGui(self):
        pass

    def unload(self):
        pass

2. Launch QGIS Desktop (the issue is at least present in 2.14 and 2.8 but does not seem to occur in early 2.x versions)
3. Encounter the following error message:

Traceback (most recent call last):
  File "C:/PROGRA~1/QGISWI~1/apps/qgis-ltr/./python\\qgis\\utils.py", line 219, in startPlugin
    plugins[packageName] = package.classFactory(iface)
  File "C:/Users/Jos� Fu�ball/.qgis2/python/plugins\\UnicodeDebug\\__init__.py", line 40, in classFactory
    return UnicodeDebug(iface)
  File "C:/Users/Jos� Fu�ball/.qgis2/python/plugins\\UnicodeDebug\\UnicodeDebug.py", line 27, in __init__
    iface.mapCanvas().mapRenderer()
  File "C:/PROGRA~1/QGISWI~1/apps/qgis-ltr/./python\\qgis\\utils.py", line 55, in showWarning
    "warning:%s\
traceback:%s" % ( warnings.formatwarning(message, category, filename, lineno), stk),
UnicodeDecodeError: 'ascii' codec can't decode byte 0xe9 in position 20: ordinal not in range(128)

Attached is some basic plugin code that can be used to reproduce the issue.

Please let me know if any further information is required.