templatefilters: raise ProgrammingError if unencodable type passed to json()
This shouldn't happen for any template data types (though I know it does
because of some templater bugs.) Let's clarify it is a bug.
#!/usr/bin/env bash
hg init remote
cd remote
echo "0" >> afile
hg add afile
hg commit -m "0.0"
echo "1" >> afile
hg commit -m "0.1"
echo "2" >> afile
hg commit -m "0.2"
echo "3" >> afile
hg commit -m "0.3"
hg update -C 0
echo "1" >> afile
hg commit -m "1.1"
echo "2" >> afile
hg commit -m "1.2"
echo "a line" > fred
echo "3" >> afile
hg add fred
hg commit -m "1.3"
hg mv afile adifferentfile
hg commit -m "1.3m"
hg update -C 3
hg mv afile anotherfile
hg commit -m "0.3m"
hg bundle -a ../remote.hg
cd ..
rm -Rf remote