contrib/tcsh_completion_build.sh

selectors2: do not use platform.system()

`platform.system()` may have a side effect spawning a shell executing
`uname -p`, which may print a warning when the current directory is removed:

  shell-init: error retrieving current directory: getcwd: cannot access parent directories: No such file or directory

This patch changes selectors2 to test the `sys.platform` string, which is a
much safer way to detect Jython.

Jython's `sys.platform` looks like this:

  Jython 2.7.1 (default:0df7adb1b397, Jun 30 2017, 19:02:43)
  [OpenJDK 64-Bit Server VM (Oracle Corporation)] on java1.8.0_144
  Type "help", "copyright", "credits" or "license" for more information.
  >>> import sys
  >>> sys.platform
  'java1.8.0_144 ( ==linux2 for targets )'

Differential Revision: https://phab.mercurial-scm.org/D1018

#!/bin/sh

#
# tcsh_completion_build.sh - script to generate tcsh completion
#
#
# Copyright (C) 2005 TK Soh.
#
# This is free software; you can redistribute it and/or modify it under
# the terms of the GNU General Public License as published by the Free
# Software Foundation; either version 2 of the License, or (at your
# option) any later version.
#
#
# Description
# -----------
# This script generates a tcsh source file to support completion
# of Mercurial commands and options.
#
# Instruction:
# -----------
# Run this script to generate the tcsh source file, and source
# the file to add command completion support for Mercurial.
#
#    tcsh% tcsh_completion.sh FILE
#    tcsh% source FILE
#
# If FILE is not specified, tcsh_completion will be generated.
#
# Bugs:
# ----
# 1. command specific options are not supported
# 2. hg commands must be specified immediately after 'hg'.
#

tcsh_file=${1-tcsh_completion}

hg_commands=`hg --debug help | \
        sed -e '1,/^list of commands:/d' \
            -e '/^enabled extensions:/,$d' \
            -e '/^additional help topics:/,$d' \
            -e '/^ [^ ]/!d; s/[,:]//g;' | \
        xargs -n5 | \
        sed -e '$!s/$/ \\\\/g; 2,$s/^ */    /g'`

hg_global_options=`hg -v help | \
        sed -e '1,/global/d;/^ *-/!d; s/ [^- ].*//' | \
        sed -e 's/ *$//; $!s/$/ \\\\/g; 2,$s/^ */    /g'`

hg_version=`hg version | sed -e '1q'`

script_name=`basename $0`

cat > $tcsh_file <<END
#
# tcsh completion for Mercurial
#
# This file has been auto-generated by $script_name for
# $hg_version
#
# Copyright (C) 2005 TK Soh.
#
# This is free software; you can redistribute it and/or modify it under
# the terms of the GNU General Public License as published by the Free
# Software Foundation; either version 2 of the License, or (at your
# option) any later version.
#

complete hg \\
  'n/--cwd/d/' 'n/-R/d/' 'n/--repository/d/' \\
  'C/-/($hg_global_options)/' \\
  'p/1/($hg_commands)/'

END