Symmetric variable fragments are not replaced in both possible directions

[Christian Kramer]

When running the transform query, the enumerator only creates one out of the several possible compounds if a fragment to be replaced is symmetric.

Here is a simplified example:
Running a transform query with this input compound

C1CCC1CCN2CC2

yields (among others) this fragmentation:

constant: C1CCC1*.C2CN2*
variable: CC

Note that the variable linker is symmetric.
The MMP database now contains transformations like

CC >> C(C)C

which should produce these two compounds:

C1CCC1C(C)CN2CC2
C1CCC1CC(C)N2CC2

, depending on which way round the transformation is applied. However, it only produces one of them. (The other one is produced too, but based on a different rule with much less pairs.)

[Christian Kramer]

Resolved with commit at 25/06/2018.