Raymond Hettinger added the comment:
New directives introduce complexity. They should be saved for pervasive and
non-trivial problems.
The motivation for this change is dubious (that a translator can't easily
handle a simple fixed string pattern). The OP grants that this is a "only
small
Zachary Ware added the comment:
Note that this is suggesting to introduce a `.. source` directive, not adjust
the existing `:source:` role.
There's nothing preventing the use of the existing pattern in special cases,
while using the new directive in the common cases. I don't have context
