Reader: images that cannot be retrieved by Photon are blank in the Reader

[designsimply]

Steps to reproduce:

1. Start a new post at https://wordpress.com/post
2. Add an external image on its own line or in an img HTML snippet
3. Publish the post and view it in the Reader

Result: the image appears fine in the post but is broken in the Reader because Photon cannot always fetch the image.

Sample image embed:

• https://cloud.githubusercontent.com/assets/1119271/11401178/48b0887c-935f-11e5-83c9-b1e0d255f361.png

Note that the image link used in the Reader https://i1.wp.com/cloud.githubusercontent.com/assets/506547/8077870/0baa1fc8-0f62-11e5-90a9-58658b6dfa7b.png?w=653&quality=80&strip=info returns, "We cannot complete this request, remote data was invalid"

Sample image HTML:

<img src="http://ksr-ugc.imgix.net/assets/003/851/970/2563ec19df134acf8ecf33e51a1e9af6_original.gif?v=1432527573&amp;w=680&amp;h=&amp;fit=max&amp;q=92&amp;s=2c43722c5d87a5ce1780cc5f75e7c00b" alt="" width="400" height="237" border="0" />

Note that the image link used in the Reader https://i1.wp.com/cloud.githubusercontent.com/assets/506547/8077870/0baa1fc8-0f62-11e5-90a9-58658b6dfa7b.png?w=653&quality=80&strip=info returns, "We cannot complete this request, remote data could not be fetched"

Original post showing a working image:

^{Seen at http://watchingstormsrollby.me/2015/11/25/imgix/ using Firefox 42.0 on Mac OS X 10.10.5}

Same post in the Reader where the image cannot be loaded:

^{Seen at https://wordpress.com/read/post/feed/40471243/873178405 using Firefox 42.0 on Mac OS X 10.10.5}

Note: it doesn't matter whether the image URL is http or https or if the blog is private—it only seems to matter that Photon sometimes cannot fetch the image.