Changelog available here
Unfortunately, I think there is still a problem. The upgrade process is prematurely terminating with the alert message:
Installing rstudio, version 1.4.1717, release 21 Upgrading to new upstream version Extracting the files of rstudio [✓] Syncing filesystems success System error. Program terminated. [Errno 18] Invalid cross-device link
journalctl doesn't appear to log anything of note — simply that the session opened, then closed. Please advise when possible.
The version that is in the unstable repo is identical to shannon. Both are on rel 21.
Right you are! Once I got back in the office and could use my other machine (which had the same problem), I tried uninstalling and reinstalling again. But there I used the package from Shannon, not Unstable. So it was just the uninstall/reinstall that corrected my problem; installing it from the Unstable repo had nothing to do with it. Thank you for helping me better understand the solution!