The 2015.03 ficfg file format is not upward compatible to the 2015.04 format

It took me a while to figure this out. We are using a standard .ficfg for our build system in which the conventions are turned off and the warnings are turned on in the globals section.
The conventions themselves were not turned off separately, so the file looked like this:

<?xml version="1.0" encoding="UTF-8"?>
<FixInsightSettings>
    <Rules>
        <Rule101 enabled="true">
            <Value>50</Value>
        </Rule101>
...
        <Rule519 enabled="true"/>
    </Rules>
    <General>
        <Conventions enabled="false"/>
        <Warnings enabled="true"/>
    </General>
</FixInsightSettings>

Fixinsight 2015.04 ignores the setting. All rules have to be enabled/disabled separately in the configuration.
I would have expected that a config file from an older version which is passed to FixInsight on the command line will lead to the same behaviour on the same and any newer version of FixInsight. If this cannot be the case (the files are incompatible). FixInsight should reject the configuration and error out instead of silently doing something different than before.