histedit: use hg.updaterepo() to avoid ui.{push|pop}buffer() hack
In some parts of code, we call hg.update() and surround that with
ui.pushbuffer() and ui.popbuffer() to suppress the output returned by
hg.update().
We have hg.updaterepo() which does not writes to UI and can be used instead.
Differential Revision: https://phab.mercurial-scm.org/D3862
== 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