C extension implementation returns paths with more hops

[glciampaglia]

When multiple paths with the same proximity are available, sometime the Cython implementation (cclosuress) returns paths with more hops than the pure Python implementation (closuress).

This bug was surfaced in knowledge_linker.tests.test_closure.test_closure_rand; it may be a Cython specific issue since regression shows it was introduced in 31589e6 (464d864fd1979229a8f5412f31ae04a5282d5848 on Github.IU), but it seems that the test started failing only recently when a newer version of Cython was used to regenerate the C extension modules.