It should not be possible to select the same language as source and target. Currently you can change the source to the same language the target is:
At the ongoing translations you can see a Bulgatian-to-Bulgarian translation probably started because of this bug.
The way it used to work (and how it should) is:
- If you have (Source: X, Target: Y), and Target is changed to X the result is (Source: Y, Target: X).
- If you have (Source: X, Target: Y), and Source is changed to Y the result is (Source: Y, Target: X).
That is, trying to select the same language becamoes a shortcut to switch source and target languages.
Given that this was working previously, it may be a good idea to write some tests that prevent future regressions.