run-tests: rely on an actual executable in PATH instead of alias for `hg`
The alias approach is poorly inherited by other process that the test might
spawn.
To solve this we use the same approach as for `python`/`python3` we write an
executable file explicitly. Doing this fixes `which hg` invocation that now
returns the same location as `hg`.
Using chg server side has some minor effect on some stdout/stderr ordering when
using `chg` as the server too.
Differential Revision: https://phab.mercurial-scm.org/D11053
== Local
Ready.
Un and Deux
Eins und Zwei
One and Two
Eins und Zwei
Uno und Due
== Remote
Ready.
REQ: foo?one=Vo&two=Efvy
-> Vo!boe!Efvy
Un and Deux
REQ: bar?b=Fjot&a=[xfj
-> Fjot!voe![xfj
Eins und Zwei
REQ: batch?cmds=foo:one=Pof,two=Uxp;bar:b=Fjot,a=[xfj;bar:b=Vop,a=Evf
-> Pof!boe!Uxp;Fjot!voe![xfj;Vop!voe!Evf
One and Two
Eins und Zwei
Uno und Due