Don't try to determine interactivity if ui() called with interactive=False. WSGI applications are not supposed to refer to sys.stdin. In ed6df6b1c29a, hgweb and hgwebdir were fixed to pass interactive=False to their ui()'s, but sys.stdin.isatty() was still called by the ui objects. This change makes sure only the ui.fixconfig() method will call ui.isatty() (by making the ui._readline() method, which is currently only called from ui.prompt(), private). ui.fixconfig() is changed to let config files override the initial interactivity setting, but not check isatty() if interactive=False was specified in the creation of the ui.

#!/bin/sh
#

hg init t
cd t
echo 1 > foo
hg ci -Am m

cd ..
hg clone t tt
cd tt
echo 1.1 > foo
hg ci -Am m

cd ../t
echo 1.2 > foo
hg ci -Am m
echo % should fail
hg pull -u ../tt

cd ../tt
echo % should fail
hg pull -u ../t
HGMERGE=true hg merge
hg ci -mm

cd ../t
echo % should work
hg pull -u ../tt