I’d like to install openHAB2 for legacy reasons (using 1.x bindings, which are not supported in OH3), so I chose “openHAB2” in openhabian.conf after flashing the current 1.6.2 release.
After openHABian did its magic, I was live with the current OH3 version, so I’m wondering, can I even use openHABian for installing OH2 in the first run somehow?
If that is possible then I would expect to do it via the clonebranch variable in the openhabian.conf file.
see the related paragraph to openhabian.conf in the documentation
Yes, use master or stable branch. There is no openHAB2 branch. Why do you start guessing names rather than read the docs ?
Unfortunately, even specifying the branch “stable” in the “openhabian.conf”, openHAB 3 is installed instead of openHAB 2. Only “master” works.
Yeah, after reading the docs and using “stable” for my first try, I picked an old backupped SD-Card and used that instead. Great to know, that “master” would have done the trick for really new installations and people without old backupped SC-Cards…
Current stable should be the same as master and stable should install OH2 so I wonder about your finding.
Master will be deleted soon so either way no, don’t remember that as it won’t do the trick in the future.
ok, but then stable will be OH3, right? And is it planned to use a “openHAB2” branch in openHABian to install OH2.5x?
so, in short it’s “stable” for openHAB2 and “openHAB3” for OH3…
kinda exactly the opposite of having “openhab2”-packages and directory names for OH2, but “openhab” for OH3! 
Yes. We discussed other variants like to make “stable” the stable OH3 branch but they all would have likely screwn up a number of user installations so we decided in favor of this.