Am 01.02.2019 um 09:30 schrieb Sven Schreiber:

          test 10pct  5pct  1pct
r <= 1 |  5.67  6.50  8.18 11.65
r = 0  | 26.35 15.66 17.95 23.52

So that's the differing conclusions from the OP, and Gretl and tsDyn again agree, urca doesn't.

Some further evidence from Stata's documentation, see
There are some critical values for the trace stat printed in the examples. Note: They have a 3-equation system, whereas in our (Reynaldo's) example we have 2 equations (2 endogenous). For the distribution (critical values) what matters is N - r_0 under H0, the number of I(1) trends under the null. You must not compare their r=0 case with our r=0 directly. This can be confusing here, but I hope I got it right.

With this in mind, Stata has (Examples 2 and 1):
20.04 where urca has 23.52 (N - r_0 = 2 at 1%)
6.65 where urca has 11.65 (N - r_0 = 1 at 1%)
15.41 where urca has 17.95 (N - r_0 = 2 at 5%)
3.76 where urca has 8.18 (N - r_0 = 1 at 5%)

Notice that with Stata's critical values the test conclusions from Reynaldo's example would agree with gretl (and tsDyn).

Both Stata and urca claim to use Osterwald-Lenum. Unfortunately I haven't been able to quickly grab a copy of that paper, so I couldn't check.
I repeat that I found some MacKinnon et al. paper which at first glance seemed to support urca.

In any case, gretl is in good company, whereas urca apparently isn't.