+DEAL::* add empty:
DEAL::Original index set:
-DEAL::{[2,3], 5, 8, 11, [13,15], 19, [21,27], [29,30], [34,37], 40, [42,43], [45,46], [49,51], 54, [56,59], [62,64], [67,70], [72,73], [76,78], [80,84], [86,88], [90,93], [95,96], [98,99]}
-DEAL::List of indices:
-DEAL::2 3 5 8 11 13 14 15 19 21 22 23 24 25 26 27 29 30 34 35 36 37 40 42 43 45 46 49 50 51 54 56 57 58 59 62 63 64 67 68 69 70 72 73 76 77 78 80 81 82 83 84 86 87 88 90 91 92 93 95 96 98 99
-DEAL::OK
+DEAL::{[3,4], 7}
+DEAL::other index set:
+DEAL::{}
+DEAL::merged index set:
+DEAL::{[3,4], 7}
+DEAL::* add self:
+DEAL::Original index set:
+DEAL::{[3,4], 7}
+DEAL::other index set:
+DEAL::{[3,4], 7}
+DEAL::merged index set:
+DEAL::{[3,4], 7}
+DEAL::* add id2:
+DEAL::Original index set:
+DEAL::{[3,4], 7}
+DEAL::other index set:
+DEAL::{0, [2,3]}
+DEAL::merged index set:
+DEAL::{0, [2,4], 7}
+DEAL::* random tests...