Thanks Abdullah and Werner!
I've briefly tested it in the latest daily that was rolled out on the PPA a few hours ago. I'm surprised it worked between a B-spline and a line! Cool!
There is one condition where it fails, and that is between a line and an arc perpendicular to it.
The line and arc were made with the polyline tool.
OS: Ubuntu 18.04.1 LTS
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.18.15099 (Git)
Build type: Release
Branch: master
Hash: 1538a14eca0879be3d223930f7e5f78d4a24691c
Python version: 2.7.15rc1
Qt version: 4.8.7
Coin version: 4.0.0a
OCC version: 7.3.0
Locale: French/Canada (fr_CA)