BF: Accept ria+https URLs in clone

[bpoldrack]

There's no actual handling of those URLs involved here. It's simply
passing it on to requests. Simply don't let clone swallow it.

[codecov]

Codecov Report

Merging #4977 into master will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master    #4977   +/-   ##
=======================================
  Coverage   89.99%   89.99%           
=======================================
  Files         292      292           
  Lines       40983    40983           
=======================================
  Hits        36884    36884           
  Misses       4099     4099           

Impacted Files	Coverage Δ
datalad/core/distributed/clone.py	88.75% <100.00%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update bcffccb...f7b4e01. Read the comment docs.