The new AST-based GitHub line resolver had an assert that tried to

ensure we were at the end of a lookup path when returning a final

result. There are actually cases where this is expected. For example, if

defining a namedtuple in code, Sphinx will (unless otherwise

specified) introspect some of the auto-generated attributes and methods,

which are auto-generated. This means there's no actual code defining

those to link to.
Rather than assert, we now assume that we're at the final result and

return it as-is.
We also bullet-proof the Assign(targets=...) lookup. The assumption

was made that each item would have an id attribute, but that's not

always the case. We now filter those out.

Unit tests pass on Python 3.6-3.11.
Built the Djblets documentation. Verified the errors went away, and that

the lines being referenced now link to the most-relevant lines in the

source.