What version are you running?
2.0.20
What's the URL of the page containing the problem?
n/a
What steps will reproduce the problem?

Upload revision 1
Publish revision 1
Upload revision 2
View changes, "Changes between revision 1 and 2"
Upload a changed revision 2
View changes, "Changes between revision 1 and 2"


What is the expected output? What do you see instead?
Expected output:

 "Changes between revision 1 and 2" in step 6 should reflect the content uploaded in step 5

 the "Diff Revision 2" download link should retrieve a file that reflects the content uploaded in step 5
Actual output:

 "Changes between revision 1 and 2" in step 6 reflects the OLD contents still uploaded in step 4

 the "Diff Revision 2" download link produces "The page you were looking for does not exist."
What operating system are you using? What browser?
Linux, Chrome
Please provide any additional information below.
So it looks as though viewing the 1-2 diff in step 4 cached thye fragments (http://hhhh/r/RRRR/diff/1-2/fragment/ffff/?index=ii&tttttttt&api_format=json) on the server-side, and uploading a new diff for revision 2 did not completely invalidate that cache.  Not a browser cache issue, it's server-side.  Manually altering the URL (removing api_format or changing ttttttt) returns the correct (expected) diff again.