Image does not fill container when HorizontalOptions are set to Fill

[czuck]

Create a content page and add the following code:

       <Grid>
                <maui:CachedImage
                   x:Name="Image"
                   Source="_image loaded from the web_.png"
                   HorizontalOptions="Fill" 
                   VerticalOptions="Start"/>
        </Grid>

Note that the image does not fill the content width. Change the maui:CachedImage to Image
If both the HorizontalOptions and VerticalOptions are set to Fill then the imagewill befull screen, but setting the VertivalOptions to Start, Center, or End will result in the image sized to its original width, not the width of the parent.
Upon further testing, this only happens when the source is defined as an URI.