Error in tensor(Ring, Ring, Join => false)

Nobody has claimed this yet.

Here's an unexpected error:
```m2
i1 : S1 = QQ[x,y, DegreeRank => 1];

i2 : S2 = QQ[x,y, DegreeRank => 2];

i3 : tensor(S1, S2, Join => false)
stdio:3:1:(3): error: with Join => false, expected degree map to return a list of length at most 1

i4 : tensor(S2, S1, Join => false)

o4 = QQ[x , y , x , y ]
0 0 1 1

o4 : PolynomialRing
```
Looking at the code, I can't figure out what was the intention here:
https://github.com/Macaulay2/M2/blob/5572c8a245d187f6c22f8eaa0b03cac0b8d86e02/M2/Macaulay2/m2/monoids.m2#L703-L705

Reproduce the two tensor calls from the issue, then inspect the linked monoids.m2 code around lines 703–705. Compare the degree-map behavior for the two ring orderings and determine the intended behavior for Join => false. Done should include a consistent result and a regression test for the reported examples.

Written by the indexing model from the issue text.