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 repo
cd repo
echo foo > foo
hg ci -qAm 'add foo' -d '0 0'
echo >> foo
hg ci -m 'change foo' -d '0 0'
hg up -qC 0
echo bar > bar
hg ci -qAm 'add bar' -d '0 0'
hg log
cd ..
hg init copy
cd copy

echo '% pull -r 0'
hg pull -qr 0 ../repo
hg log

echo '% pull -r 1'
hg pull -qr 1 ../repo
hg log

# this used to abort: received changelog group is empty
echo '% pull -r 1 again'
hg pull -qr 1 ../repo