I have tried upgrading my R6220 from rc1 to rc2 and version still states RC1 at the botton to each lucy page.
Could anyone explain if the device not upgrading is related to these lines of the release notes :
When upgrading from 19.07.0-rc1, if you are affected by the sysupgrade bug on ar71xx, you need to manually edit /lib/upgrade/stage2 and add /usr/share/libubox/jshn.sh to list of files in the install_file line (around line 51). This amounts to manually applying this patch.
If yes, could one provide a little bit more explanation as to sequence of operations to achieve that.
Quite possibly you are hit with that problem. The list of files used in the sysupgrade process is missing one file, which affects some routers (and maybe even not always).
There is not much more to explain. I split the sentence into three steps:
login to the router with ssh
use your usual text editor (e.g. "nano") to edit /lib/upgrade/stage2
edit the file on line 51 (?) and add /usr/share/libubox/jshn.sh to the list that defines the files for the install_file list. (like you see in the linked patch, the line ends with "$RAMFS_COPY_DATA". add the filename before that, just like in the patch.)