Setup:
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* gssdp: 3a45f61ee50a1d30574da48f6b2bbbfb9b6574b6
* gupnp: 21fccb67689e717828c2fba44aa72d63d2321cd0
* gupnp-av: bcb1e53b5239e77cd2333f3ab471cdb95bfc4584
* gupnp-dlna: fed5da3d1b79a2775e0d7ebaa8b03c4f349ee0dd
* media-service-upnp: 7a0b804f6c3573c774262a39b0d4e9a9fecd0b0b
* Rygel 0.17.7.37-8f125b: 8f125bedbfb444e59db81fac76fd400bb13c20b1

Pre-conditions:
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* Launch: Rygel, Media Service UPnP, Gimp, media console
* Rygel (DMS) shares one jpg (I used 62.jpg 480x480 px)

Steps:
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1 . In media console, print properties of the jpg
2 . Open the jpeg with Gimp, modify the resolution (Right clic, Image->Scale Image) and save it (File->Overwrite).
3 . In media console, print again properties of the jpg

Actual result:
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1 . Properties indicate: "UpdateCount": 0, "Width": 480
3 . Properties indicate: "UpdateCount": 0, "Width": 470

Expected result:
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3 . updateCount property MUST be incremented by one (“1”)

Information
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In librygel-server/rygel-media-item.vala source:

    if (this is TrackableItem) {
        // This is attribute is mandatory for track changes
        // implementation. We don't really support updating the resources
        // so we just set it to 0.
        res.update_count = 0;
    }