[QGIS-Developer] Strange Behavior with QgsProcessingParameterNumber - Bug?

[C Hamilton]

In a processing algorithm I have a double QgsProcessingParameterNumber
where I have set the number of decimals metadata to be 20.

param = QgsProcessingParameterNumber(
            'NUMBER',
            tr('Number'),
            QgsProcessingParameterNumber.Double,
            defaultValue=0,
            optional=False)
        param.setMetadata({'widget_wrapper': { 'decimals': 20 }})
        self.addParameter(param)

In the processing popup, if I enter a number with less than 20 digits then
the rest of the digits become some random number. For example if I enter

-0.1556640799496235

the displayed result is

-0.15566407994962350170

I would think that if it pads with extra digits to fill out to 20, the
digits should be 0. Have I exceeded the number of acceptable decimal
digits, or is this a bug?

Thanks,

Calvin
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