Deprecation warnings have a parameter which is interpreted as a trac ticket
number, and output a second line after the warning text, of the form
See https://trac.sagemath.org/12345 for details.
Is the solution simply to replace the template for that output with a
suitable GitHub issue number (or
sage: import warnings
sage: warnings.filterwarnings('always',".*", DeprecationWarning)
sage: deprecation(3,"m")
Hi sage-devel,
On my Sage installation, as well as on David Lucas' (having different
Linux distros), the following *does not* print the expected deprecation
warning in the Sage shell or
