Substructure matcher finds implicit hydrogens as atoms

[AlexanderSavelyev]

Steps to Reproduce

smiles = "C";
smarts = "[!#6]";
Indigo indigo = new Indigo();
IndigoObject pattern = indigo.loadSmarts(smarts);
IndigoObject molecule = indigo.loadMolecule(smiles);
IndigoObject match = indigo.substructureMatcher(molecule).match(pattern);
if (match !=null) // a match is produced here. Working correctly for version 1.12. 

Actual behavior
Match returns non-zero result for implicit hydrogens

Expected behavior
There should be no match for implicit hydrogens

Environment details:

• 1.18