Update the instructions on configuring git's push.default.
Misc improvements to `net/uri-codec'.

Fix a bug in encoding strings with characters between 128 and 256, avoid
extra bindings for conversion vectors; remove calling `noels-tests' from
`main' since it's already called from `tests', etc.
Protect strings from regexps.

Fixes PR13768.
Typo in error.

Fixes PR13769.