If someone knows how to configure Jack2 project in a IDE (Eclipse, Netbeans, whatever) I would be very interested.

Will this introduce any incompatibilities, e.g. with existing setups people might be using?

Berkeley DB will be dropped from Fedora soon I think

It should not introduce any incompatibilities.
Aliases might still be used alongside properties even if aliases are deprecated in Jack.

A quick search about Berkeley DB shows that
- Fedora will switch to Sqlite for RPM https://www.phoronix.com/scan.php?page=news_item&px=Fedora-RPMDB-To-SQLite
- keep multiples version available https://fedoraproject.org/wiki/Changes/BerkeleyDB_6

We don't seem to have Berkeley DB v6 (the one licensed AGPLv3+) yet, the change you linked never seems to have been completed.

However, as jack2 has parts licensed as GPLv2-only (which is incompatible with AGPLv3) we should prevent that it is ever built against the so-licensed libdb, should it become packaged in Fedora at some point. Please add < 6 to this line and a comment before it à la # The license of Berkeley DB v6 is incompatible with GPLv2.

@tartina, I haven't seen concrete plans to drop libdb from Fedora, but if it ever happens, we can just revert this change. For the time being, I think it's fine to have that feature -- we don't have quite the same stringent requirements as the RPM folks.

@tartina, I haven't seen concrete plans to drop libdb from Fedora, but if it ever happens, we can just revert this change. For the time being, I think it's fine to have that feature -- we don't have quite the same stringent requirements as the RPM folks.

I agree.
I thought RPM was the only packege to still use bdb, when they decided to switch to sqlite it seemed to me the end of bdb.
And we can revert if needed, so
+1 for me

I added the requested limitation to avoid AGPLv3 (precisely at < 6.0.20) according to Wikipedia.
Note that I am not so sure about "incompatibilities" https://en.wikipedia.org/wiki/Comparison_of_free_and_open-source_software_licenses but I do not want (nor can't ) debate this topic

Better to stay on the safe side anyway. I will also inform Jack2 about the alternatives (SQLite, LMDB ....)

Thankfully we don't have to debate this, as the legal types did this already and summarized it on the Licensing wiki page in the List of Good Licenses:

Full Name: Affero General Public License 3.0 or later
Short Name: AGPLv3+
FSF Free?: Yes
GPLv2 Compat?: NO
GPLv3 Compat?: Sortof
Upstream URL: http://www.fsf.org/licensing/licenses/agpl-3.0.html

Is there something I should do for this pull request?
Or are we waiting for some kind of monthly global release?

No, nothing for you to do, we just dropped the ball. Sorry and thanks for the contribution!