Question/answer shared by @swenzel was useful to understand the reason (thanks) but I think precise steps to overcome this warning are needed.
As stated here you may need to change the login shell for your user in order to use the shell of your preference by default, in my case is bash
so I made some changes the way I launch my terminal.
chsh
is advised but in my particular case I'm using ConEmu Windows Terminal with Cygwin in a Windows 10 environment; sh.exe
is used by default thus this RVM warning...
chsh
is not available in Cygwin, so I followed this reccomendation that states that:
it is just a matter of changing (...) whatever shortcut you
are using to start cygwin to call {prefered shell here} instead
I hope this is useful. Gretings!