pager: add a test of --pager=no functionality

I'm about to upend the pager universe, but I would like to not regress
anything.

tests/test-pager.t

@@ -1,229 +1,234 b''
   $ cat >> fakepager.py <<EOF
   > import sys
   > for line in sys.stdin:
   >     sys.stdout.write('paged! %r\n' % line)
   > EOF
 
 Enable ui.formatted because pager won't fire without it, and set up
 pager and tell it to use our fake pager that lets us see when the
 pager was running.
   $ cat >> $HGRCPATH <<EOF
   > [ui]
   > formatted = yes
   > [extensions]
   > pager=
   > [pager]
   > pager = python $TESTTMP/fakepager.py
   > EOF
 
   $ hg init repo
   $ cd repo
   $ echo a >> a
   $ hg add a
   $ hg ci -m 'add a'
   $ for x in `python $TESTDIR/seq.py 1 10`; do
   >   echo a $x >> a
   >   hg ci -m "modify a $x"
   > done
 
 By default diff and log are paged, but summary is not:
 
   $ hg diff -c 2 --pager=yes
   paged! 'diff -r f4be7687d414 -r bce265549556 a\n'
   paged! '--- a/a\tThu Jan 01 00:00:00 1970 +0000\n'
   paged! '+++ b/a\tThu Jan 01 00:00:00 1970 +0000\n'
   paged! '@@ -1,2 +1,3 @@\n'
   paged! ' a\n'
   paged! ' a 1\n'
   paged! '+a 2\n'
 
   $ hg log --limit 2
   paged! 'changeset:   10:46106edeeb38\n'
   paged! 'tag:         tip\n'
   paged! 'user:        test\n'
   paged! 'date:        Thu Jan 01 00:00:00 1970 +0000\n'
   paged! 'summary:     modify a 10\n'
   paged! '\n'
   paged! 'changeset:   9:6dd8ea7dd621\n'
   paged! 'user:        test\n'
   paged! 'date:        Thu Jan 01 00:00:00 1970 +0000\n'
   paged! 'summary:     modify a 9\n'
   paged! '\n'
 
   $ hg summary
   parent: 10:46106edeeb38 tip
    modify a 10
   branch: default
   commit: (clean)
   update: (current)
   phases: 11 draft
 
 We can enable the pager on summary:
 
   $ hg --config pager.attend-summary=yes summary
   paged! 'parent: 10:46106edeeb38 tip\n'
   paged! ' modify a 10\n'
   paged! 'branch: default\n'
   paged! 'commit: (clean)\n'
   paged! 'update: (current)\n'
   paged! 'phases: 11 draft\n'
 
 If we completely change the attend list that's respected:
 
   $ hg --config pager.attend-diff=no diff -c 2
   diff -r f4be7687d414 -r bce265549556 a
   --- a/a	Thu Jan 01 00:00:00 1970 +0000
   +++ b/a	Thu Jan 01 00:00:00 1970 +0000
   @@ -1,2 +1,3 @@
    a
    a 1
   +a 2
 
   $ hg --config pager.attend=summary diff -c 2
   diff -r f4be7687d414 -r bce265549556 a
   --- a/a	Thu Jan 01 00:00:00 1970 +0000
   +++ b/a	Thu Jan 01 00:00:00 1970 +0000
   @@ -1,2 +1,3 @@
    a
    a 1
   +a 2
 
 If 'log' is in attend, then 'history' should also be paged:
   $ hg history --limit 2 --config pager.attend=log
   paged! 'changeset:   10:46106edeeb38\n'
   paged! 'tag:         tip\n'
   paged! 'user:        test\n'
   paged! 'date:        Thu Jan 01 00:00:00 1970 +0000\n'
   paged! 'summary:     modify a 10\n'
   paged! '\n'
   paged! 'changeset:   9:6dd8ea7dd621\n'
   paged! 'user:        test\n'
   paged! 'date:        Thu Jan 01 00:00:00 1970 +0000\n'
   paged! 'summary:     modify a 9\n'
   paged! '\n'
 
 Possible bug: history is explicitly ignored in pager config, but
 because log is in the attend list it still gets pager treatment.
 
   $ hg history --limit 2 --config pager.attend=log \
   >   --config pager.ignore=history
   paged! 'changeset:   10:46106edeeb38\n'
   paged! 'tag:         tip\n'
   paged! 'user:        test\n'
   paged! 'date:        Thu Jan 01 00:00:00 1970 +0000\n'
   paged! 'summary:     modify a 10\n'
   paged! '\n'
   paged! 'changeset:   9:6dd8ea7dd621\n'
   paged! 'user:        test\n'
   paged! 'date:        Thu Jan 01 00:00:00 1970 +0000\n'
   paged! 'summary:     modify a 9\n'
   paged! '\n'
 
 Possible bug: history is explicitly marked as attend-history=no, but
 it doesn't fail to get paged because log is still in the attend list.
 
   $ hg history --limit 2 --config pager.attend-history=no
   paged! 'changeset:   10:46106edeeb38\n'
   paged! 'tag:         tip\n'
   paged! 'user:        test\n'
   paged! 'date:        Thu Jan 01 00:00:00 1970 +0000\n'
   paged! 'summary:     modify a 10\n'
   paged! '\n'
   paged! 'changeset:   9:6dd8ea7dd621\n'
   paged! 'user:        test\n'
   paged! 'date:        Thu Jan 01 00:00:00 1970 +0000\n'
   paged! 'summary:     modify a 9\n'
   paged! '\n'
 
 Possible bug: disabling pager for log but enabling it for history
 doesn't result in history being paged.
 
   $ hg history --limit 2 --config pager.attend-log=no \
   > --config pager.attend-history=yes
   changeset:   10:46106edeeb38
   tag:         tip
   user:        test
   date:        Thu Jan 01 00:00:00 1970 +0000
   summary:     modify a 10
   
   changeset:   9:6dd8ea7dd621
   user:        test
   date:        Thu Jan 01 00:00:00 1970 +0000
   summary:     modify a 9
   
 
 Pager should not start if stdout is not a tty.
 
   $ hg log -l1 -q --config ui.formatted=False
   10:46106edeeb38
 
 Pager with color enabled allows colors to come through by default,
 even though stdout is no longer a tty.
   $ cat >> $HGRCPATH <<EOF
   > [extensions]
   > color=
   > [color]
   > mode = ansi
   > EOF
   $ hg log --limit 3
   paged! '\x1b[0;33mchangeset:   10:46106edeeb38\x1b[0m\n'
   paged! 'tag:         tip\n'
   paged! 'user:        test\n'
   paged! 'date:        Thu Jan 01 00:00:00 1970 +0000\n'
   paged! 'summary:     modify a 10\n'
   paged! '\n'
   paged! '\x1b[0;33mchangeset:   9:6dd8ea7dd621\x1b[0m\n'
   paged! 'user:        test\n'
   paged! 'date:        Thu Jan 01 00:00:00 1970 +0000\n'
   paged! 'summary:     modify a 9\n'
   paged! '\n'
   paged! '\x1b[0;33mchangeset:   8:cff05a6312fe\x1b[0m\n'
   paged! 'user:        test\n'
   paged! 'date:        Thu Jan 01 00:00:00 1970 +0000\n'
   paged! 'summary:     modify a 8\n'
   paged! '\n'
 
 Pager works with shell aliases.
 
   $ cat >> $HGRCPATH <<EOF
   > [alias]
   > echoa = !echo a
   > EOF
 
   $ hg echoa
   a
   $ hg --config pager.attend-echoa=yes echoa
   paged! 'a\n'
 
 Pager works with hg aliases including environment variables.
 
   $ cat >> $HGRCPATH <<'EOF'
   > [alias]
   > printa = log -T "$A\n" -r 0
   > EOF
 
   $ A=1 hg --config pager.attend-printa=yes printa
   paged! '1\n'
   $ A=2 hg --config pager.attend-printa=yes printa
   paged! '2\n'
 
+Something that's explicitly attended is still not paginated if the
+pager is globally set to off using a flag:
+  $ A=2 hg --config pager.attend-printa=yes printa --pager=no
+  2
+
 Pager should not override the exit code of other commands
 
   $ cat >> $TESTTMP/fortytwo.py <<'EOF'
   > from mercurial import cmdutil, commands
   > cmdtable = {}
   > command = cmdutil.command(cmdtable)
   > @command('fortytwo', [], 'fortytwo', norepo=True)
   > def fortytwo(ui, *opts):
   >     ui.write('42\n')
   >     return 42
   > EOF
 
   $ cat >> $HGRCPATH <<'EOF'
   > [extensions]
   > fortytwo = $TESTTMP/fortytwo.py
   > EOF
 
   $ hg fortytwo --pager=on
   paged! '42\n'
   [42]