windows: add windows behavior on broken pager

Apparently, Windows has "better" behavior than Unix in this case. This is an
edge case that led me down a rabbit hole, only to find a bug in the Python
documentation... I am not planning on trying to reproduce the same behavior
on Unix systems since it's not really useful, but other people are welcome to!

Differential Revision: https://phab.mercurial-scm.org/D11000

tests/test-pager.t

@@ -1,416 +1,438 b''
   $ cat >> fakepager.py <<EOF
   > import sys
   > printed = False
   > for line in sys.stdin:
   >     sys.stdout.write('paged! %r\n' % line)
   >     printed = True
   > if not printed:
   >     sys.stdout.write('paged empty output!\n')
   > 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 >> $HGRCPATH <<EOF
   > [ui]
   > formatted = yes
   > color = no
   > [pager]
   > pager = "$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 id 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 id
   46106edeeb38 tip
 
 We can control the pager from the config
 
   $ hg log --limit 1 --config 'ui.paginate=False'
   changeset:   10:46106edeeb38
   tag:         tip
   user:        test
   date:        Thu Jan 01 00:00:00 1970 +0000
   summary:     modify a 10
   
   $ hg log --limit 1 --config 'ui.paginate=0'
   changeset:   10:46106edeeb38
   tag:         tip
   user:        test
   date:        Thu Jan 01 00:00:00 1970 +0000
   summary:     modify a 10
   
   $ hg log --limit 1 --config 'ui.paginate=1'
   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'
 
 explicit --pager=on should take precedence over other configurations
 (issue5580)
 
   $ cat >> $HGRCPATH <<EOF
   > [ui]
   > paginate = false
   > EOF
   $ hg log --limit 1 --pager=on
   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'
 
   $ cat >> $HGRCPATH <<EOF
   > [ui]
   > # true is default value of ui.paginate
   > paginate = true
   > EOF
   $ hg log --limit 1 --pager=off
   changeset:   10:46106edeeb38
   tag:         tip
   user:        test
   date:        Thu Jan 01 00:00:00 1970 +0000
   summary:     modify a 10
   
 
 We can enable the pager on id:
 
 BROKEN: should be paged
   $ hg --config pager.attend-id=yes id
   46106edeeb38 tip
 
 Setting attend-$COMMAND to a false value works, even with pager in
 core:
   $ 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
 
 Command aliases should have same behavior as main command
 
   $ hg history --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'
 
 Abbreviated command alias should also be paged
 
   $ hg hist -l 1
   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'
 
 Attend for an abbreviated command does not work
 
   $ hg --config pager.attend-ident=true ident
   46106edeeb38 tip
 
   $ hg --config extensions.pager= --config pager.attend-ident=true ident
   46106edeeb38 tip
 
 Pager should not start if stdout is not a tty.
 
   $ hg log -l1 -q --config ui.formatted=False
   10:46106edeeb38
 
 Pager should be disabled if pager.pager is empty (otherwise the output would
 be silently lost.)
 
   $ hg log -l1 -q --config pager.pager=
   10:46106edeeb38
 
 Pager with color enabled allows colors to come through by default,
 even though stdout is no longer a tty.
   $ cat >> $HGRCPATH <<EOF
   > [ui]
   > color = always
   > [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'
 
 #if no-chg
 An invalid pager command name is reported sensibly if we don't have to
 use shell=True in the subprocess call:
   $ hg log --limit 3 --config pager.pager=this-command-better-never-exist
   missing pager command 'this-command-better-never-exist', skipping pager
   \x1b[0;33mchangeset:   10:46106edeeb38\x1b[0m (esc)
   tag:         tip
   user:        test
   date:        Thu Jan 01 00:00:00 1970 +0000
   summary:     modify a 10
   
   \x1b[0;33mchangeset:   9:6dd8ea7dd621\x1b[0m (esc)
   user:        test
   date:        Thu Jan 01 00:00:00 1970 +0000
   summary:     modify a 9
   
   \x1b[0;33mchangeset:   8:cff05a6312fe\x1b[0m (esc)
   user:        test
   date:        Thu Jan 01 00:00:00 1970 +0000
   summary:     modify a 8
   
 #endif
 
 A complicated pager command gets worse behavior. Bonus points if you can
-improve this.
+improve this. Windows apparently does this better?
+#if windows
   $ hg log --limit 3 \
   >   --config pager.pager='this-command-better-never-exist --seriously' \
   >  2>/dev/null || true
+  \x1b[0;33mchangeset:   10:46106edeeb38\x1b[0m (esc)
+  tag:         tip
+  user:        test
+  date:        Thu Jan 01 00:00:00 1970 +0000
+  summary:     modify a 10
+  
+  \x1b[0;33mchangeset:   9:6dd8ea7dd621\x1b[0m (esc)
+  user:        test
+  date:        Thu Jan 01 00:00:00 1970 +0000
+  summary:     modify a 9
+  
+  \x1b[0;33mchangeset:   8:cff05a6312fe\x1b[0m (esc)
+  user:        test
+  date:        Thu Jan 01 00:00:00 1970 +0000
+  summary:     modify a 8
+  
+#else
+  $ hg log --limit 3 \
+  >   --config pager.pager='this-command-better-never-exist --seriously' \
+  >  2>/dev/null || true
+#endif
 
 Pager works with shell aliases.
 
   $ cat >> $HGRCPATH <<EOF
   > [alias]
   > echoa = !echo a
   > EOF
 
   $ hg echoa
   a
 BROKEN: should be paged
   $ hg --config pager.attend-echoa=yes echoa
   a
 
 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 commands, registrar
   > cmdtable = {}
   > command = registrar.command(cmdtable)
   > @command(b'fortytwo', [], b'fortytwo', norepo=True)
   > def fortytwo(ui, *opts):
   >     ui.write(b'42\n')
   >     return 42
   > EOF
 
   $ cat >> $HGRCPATH <<'EOF'
   > [extensions]
   > fortytwo = $TESTTMP/fortytwo.py
   > EOF
 
   $ hg fortytwo --pager=on
   paged! '42\n'
   [42]
 
 A command that asks for paging using ui.pager() directly works:
   $ hg blame a
   paged! ' 0: a\n'
   paged! ' 1: a 1\n'
   paged! ' 2: a 2\n'
   paged! ' 3: a 3\n'
   paged! ' 4: a 4\n'
   paged! ' 5: a 5\n'
   paged! ' 6: a 6\n'
   paged! ' 7: a 7\n'
   paged! ' 8: a 8\n'
   paged! ' 9: a 9\n'
   paged! '10: a 10\n'
 but not with HGPLAIN
   $ HGPLAIN=1 hg blame a
    0: a
    1: a 1
    2: a 2
    3: a 3
    4: a 4
    5: a 5
    6: a 6
    7: a 7
    8: a 8
    9: a 9
   10: a 10
 explicit flags work too:
   $ hg blame --pager=no a
    0: a
    1: a 1
    2: a 2
    3: a 3
    4: a 4
    5: a 5
    6: a 6
    7: a 7
    8: a 8
    9: a 9
   10: a 10
 
 A command with --output option:
 
   $ hg cat -r0 a
   paged! 'a\n'
   $ hg cat -r0 a --output=-
   paged! 'a\n'
   $ hg cat -r0 a --output=out
 
   $ hg export -r0
   paged! '# HG changeset patch\n'
   paged! '# User test\n'
   paged! '# Date 0 0\n'
   paged! '#      Thu Jan 01 00:00:00 1970 +0000\n'
   paged! '# Node ID 1f0dee641bb7258c56bd60e93edfa2405381c41e\n'
   paged! '# Parent  0000000000000000000000000000000000000000\n'
   paged! 'add a\n'
   paged! '\n'
   paged! '\x1b[0;1mdiff -r 000000000000 -r 1f0dee641bb7 a\x1b[0m\n'
   paged! '\x1b[0;31;1m--- /dev/null\tThu Jan 01 00:00:00 1970 +0000\x1b[0m\n'
   paged! '\x1b[0;32;1m+++ b/a\tThu Jan 01 00:00:00 1970 +0000\x1b[0m\n'
   paged! '\x1b[0;35m@@ -0,0 +1,1 @@\x1b[0m\n'
   paged! '\x1b[0;32m+a\x1b[0m\n'
   $ hg export -r0 -o -
   paged! '# HG changeset patch\n'
   paged! '# User test\n'
   paged! '# Date 0 0\n'
   paged! '#      Thu Jan 01 00:00:00 1970 +0000\n'
   paged! '# Node ID 1f0dee641bb7258c56bd60e93edfa2405381c41e\n'
   paged! '# Parent  0000000000000000000000000000000000000000\n'
   paged! 'add a\n'
   paged! '\n'
   paged! '\x1b[0;1mdiff -r 000000000000 -r 1f0dee641bb7 a\x1b[0m\n'
   paged! '\x1b[0;31;1m--- /dev/null\tThu Jan 01 00:00:00 1970 +0000\x1b[0m\n'
   paged! '\x1b[0;32;1m+++ b/a\tThu Jan 01 00:00:00 1970 +0000\x1b[0m\n'
   paged! '\x1b[0;35m@@ -0,0 +1,1 @@\x1b[0m\n'
   paged! '\x1b[0;32m+a\x1b[0m\n'
   $ hg export -r0 -o out
 
   $ rm out
 
 Put annotate in the ignore list for pager:
   $ cat >> $HGRCPATH <<EOF
   > [pager]
   > ignore = annotate
   > EOF
   $ hg blame a
    0: a
    1: a 1
    2: a 2
    3: a 3
    4: a 4
    5: a 5
    6: a 6
    7: a 7
    8: a 8
    9: a 9
   10: a 10
 
 During pushbuffer, pager should not start:
   $ cat > $TESTTMP/pushbufferpager.py <<EOF
   > def uisetup(ui):
   >     ui.pushbuffer()
   >     ui.pager(b'mycmd')
   >     ui.write(b'content\n')
   >     ui.write(ui.popbuffer())
   > EOF
 
   $ echo append >> a
   $ hg --config extensions.pushbuffer=$TESTTMP/pushbufferpager.py status --color=off
   content
   paged! 'M a\n'
 
 Environment variables like LESS and LV are set automatically:
   $ cat > $TESTTMP/printlesslv.py <<EOF
   > from __future__ import absolute_import
   > import os
   > import sys
   > sys.stdin.read()
   > for name in ['LESS', 'LV']:
   >     sys.stdout.write(('%s=%s\n') % (name, os.environ.get(name, '-')))
   > sys.stdout.flush()
   > EOF
 
   $ cat >> $HGRCPATH <<EOF
   > [alias]
   > noop = log -r 0 -T ''
   > [ui]
   > formatted=1
   > [pager]
   > pager = "$PYTHON" $TESTTMP/printlesslv.py
   > EOF
   $ unset LESS
   $ unset LV
   $ hg noop --pager=on
   LESS=FRX
   LV=-c
   $ LESS=EFGH hg noop --pager=on
   LESS=EFGH
   LV=-c