FieldRefs not working with XML comments

Today I was working on a SharePoint 2010 project where the custom fields and content types where provisioned using a feature. After the feature was activated the custom fields and content types where provisioned in SharePoint, except the content type contained no fields. The element manifest file contained the following xml:

  <!-- Base Page -->
<ContentType ID="0x010100C568DB52D9D0A1...84E219954237AF3901"
              Name="Basepage"
              Description="Basepage"
              Group="Publishing"
              Sealed="TRUE"
              Inherits="TRUE"
              Version="1">
  <FieldRefs>
    <!-- Originating from MOSS -->
    <FieldRef ID="{b66e9b50-a28e-469b-b1a0-af0e45486874}"
            Name="Keywords" />
    <!-- Custom fields -->
    <FieldRef ID="{30607e4e-a3e1-4662-9766-56e1faedb875}"
            Name="AdminComments" />
  </FieldRefs>
</ContentType>

The ULS logs showed no errors and I couldn’t figure out what the problem was because the same element manifest file was used in SharePoint 2007. After the stripping the file I figured out that the xml comments were causing the problem. Now my element manifest contains the following:

<ContentType ID="0x010100C568DB52D9D0A1...84E219954237AF3901"
              Name="Basepage"
              Description="Basepage"
              Group="Publishing"
              Sealed="TRUE"
              Inherits="TRUE"
              Version="1">
  <FieldRefs>
    <FieldRef ID="{b66e9b50-a28e-469b-b1a0-af0e45486874}"
            Name="Keywords" />
    <FieldRef ID="{30607e4e-a3e1-4662-9766-56e1faedb875}"
            Name="AdminComments" />
  </FieldRefs>
</ContentType>

The content is the same except the comments are missing.