File bug reports or feature requests, and make contributions (e.g. code patches), by opening a “new issue” on GitHub:
NumPy Issues: https://github.com/numpy/numpy/issues
Please give as much information as you can in the ticket. It is extremely useful if you can supply a small self-contained code snippet that reproduces the problem. Also specify the component, the version you are referring to and the milestone.
Report bugs to the appropriate GitHub project (there is one for NumPy and a different one for SciPy).
More information can be found on the https://www.scipy.org/scipylib/dev-zone.html website.