pyside-uic: "ValueError: unknown baseclass QOpenGLWidget"

[gim-]

PySide's UIC can't generate a class that contains a custom widget like this:

<customwidgets>
<customwidget>
<class>MyOwnOpenGLWidget</class>
<extends>QOpenGLWidget</extends>
<header>MyOwnOpenGLWidget</header>
</customwidget>
</customwidgets>

PyQt5 UIC version doesn't have this issue.

% pyside-uic --version
PySide User Interface Compiler version 0.2.15, running on PySide 1.2.4.

% pyside-uic untitled.ui -o test.py -d
Traceback (most recent call last):
  File "/usr/lib/python3.5/site-packages/pysideuic/Compiler/qobjectcreator.py", line 93, in _resolveBaseclass
    baseClass = self._widgets[baseClass][0]
KeyError: 'QOpenGLWidget'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/lib/python3.5/site-packages/pysideuic/port_v3/invoke.py", line 34, in invoke
    exit_status = driver.invoke()
  File "/usr/lib/python3.5/site-packages/pysideuic/driver.py", line 60, in invoke
    self._generate()
  File "/usr/lib/python3.5/site-packages/pysideuic/driver.py", line 94, in _generate
    compileUi(self._ui_file, pyfile, self._opts.execute, self._opts.indent, self._opts.from_imports)
  File "/usr/lib/python3.5/site-packages/pysideuic/__init__.py", line 142, in compileUi
    winfo = compiler.UICompiler().compileUi(uifile, pyfile, from_imports)
  File "/usr/lib/python3.5/site-packages/pysideuic/Compiler/compiler.py", line 91, in compileUi
    w = self.parse(input_stream)
  File "/usr/lib/python3.5/site-packages/pysideuic/uiparser.py", line 867, in parse
    actor(elem)
  File "/usr/lib/python3.5/site-packages/pysideuic/uiparser.py", line 710, in createUserInterface
    self.traverseWidgetTree(elem)
  File "/usr/lib/python3.5/site-packages/pysideuic/uiparser.py", line 688, in traverseWidgetTree
    handler(self, child)
  File "/usr/lib/python3.5/site-packages/pysideuic/uiparser.py", line 423, in createLayout
    self.traverseWidgetTree(elem)
  File "/usr/lib/python3.5/site-packages/pysideuic/uiparser.py", line 688, in traverseWidgetTree
    handler(self, child)
  File "/usr/lib/python3.5/site-packages/pysideuic/uiparser.py", line 460, in handleItem
    self.traverseWidgetTree(elem)
  File "/usr/lib/python3.5/site-packages/pysideuic/uiparser.py", line 688, in traverseWidgetTree
    handler(self, child)
  File "/usr/lib/python3.5/site-packages/pysideuic/uiparser.py", line 189, in createWidget
    self.stack.push(self.setupObject(widget_class, parent, elem))
  File "/usr/lib/python3.5/site-packages/pysideuic/uiparser.py", line 152, in setupObject
    obj =  self.factory.createQObject(clsname, name, args, is_attribute)
  File "/usr/lib/python3.5/site-packages/pysideuic/objcreator.py", line 87, in createQObject
    classType = self.findQObjectType(classname)
  File "/usr/lib/python3.5/site-packages/pysideuic/objcreator.py", line 97, in findQObjectType
    w = module.search(classname)
  File "/usr/lib/python3.5/site-packages/pysideuic/Compiler/qobjectcreator.py", line 104, in search
    baseClass = self._resolveBaseclass(self._widgets[cls][0])
  File "/usr/lib/python3.5/site-packages/pysideuic/Compiler/qobjectcreator.py", line 98, in _resolveBaseclass
    raise ValueError("unknown baseclass %s" % baseClass)
ValueError: unknown baseclass QOpenGLWidget

untitled_ui.zip