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.
changeset: 0:9426b370c206
tag: tip
user: My Name <myname@example.com>
date: Mon Jan 12 13:46:40 1970 +0000
summary: commit-1
changeset: 1:4997f15a1b24
tag: tip
user: foo@bar.com
date: Mon Jan 12 13:46:40 1970 +0000
summary: commit-1
changeset: 2:72b8012b424e
tag: tip
user: foobar <foo@bar.com>
date: Mon Jan 12 13:46:40 1970 +0000
summary: commit-1
changeset: 3:35ff3067bedd
tag: tip
user: foo@bar.com
date: Mon Jan 12 13:46:40 1970 +0000
summary: commit-1
transaction abort!
rollback completed
abort: Please specify a username.
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