Assertion failure while creating editor

[RoelVugts]

When running pluginval in debug mode I hit an assertion failure:

Completed tests in pluginval / Open editor whilst processing
-----------------------------------------------------------------
Starting tests in: pluginval / Editor...

Time taken to open editor (cold): 210 ms
JUCE Assertion failure in juce_AudioProcessor.cpp:915
Exception: EXC_BREAKPOINT (code=1, subcode=0x1344fba20)

It's the following assertion:

    if (activeEditor != nullptr)
    {
        // There's already an active editor! Before calling createEditorIfNeeded(),
        // you should check whether there's already an editor using getActiveEditor().
        jassertfalse;
        return nullptr;
    }

I first assumed it was some bug in my plugin but it's also happening in the AudioPluginDemo from JUCE. This is only in the develop version, if I built from tag v1.0.4 I don't hit any assertions. Maybe it's already on the radar but I figured it might be good to know.

Additional info:

• Pluginval built from the develop branch (82bab76)
• Happens in both AU and VST3
• Pluginval and AudioPluginDemo built with JUCE 8.0.10 (a2a9c54)
• No tests failing when plugin is built in release mode.