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
echo a > a
hg commit -A -ma

echo a >> a
hg commit -mb

echo a >> a
hg commit -mc

hg up 1
echo a >> a
hg commit -md

hg up 1
echo a >> a
hg commit -me

hg up 1
echo % should fail because not at a head
hg merge

hg up
echo % should fail because \> 2 heads
hg merge

echo % should succeed
hg merge 2
hg commit -mm1

echo % should succeed - 2 heads
hg merge
hg commit -mm2

echo % should fail because at tip
hg merge

hg up 0
echo % should fail because 1 head
hg merge

true