[PATCH 1 of 5 stable] crecord: use try/except for import of curses

[Yuya Nishihara]

On Tue, 15 Dec 2015 16:06:12 -0800, Sean Farley wrote:
> # HG changeset patch
> # User Sean Farley <sean at farley.io>
> # Date 1450223509 28800
> #      Tue Dec 15 15:51:49 2015 -0800
> # Branch stable
> # Node ID 7ceba88969e51bb825748f69b45e4677e0a02815
> # Parent  59d5f619e69ec43f1957eddd85d4e1deddd64925
> crecord: use try/except for import of curses
> 
> Not only does this improve fragility with 'if os.name == ...' it will help
> future patches enable the behavior to fallback to use plain record when curses
> is unavailable (e.g. python compiled without curses support).
> 
> diff --git a/mercurial/crecord.py b/mercurial/crecord.py
> --- a/mercurial/crecord.py
> +++ b/mercurial/crecord.py
> @@ -28,16 +28,15 @@ from . import (
>  
>  # This is required for ncurses to display non-ASCII characters in default user
>  # locale encoding correctly.  --immerrr
>  locale.setlocale(locale.LC_ALL, '')
>  
> -# os.name is one of: 'posix', 'nt', 'dos', 'os2', 'mac', or 'ce'
> -if os.name == 'posix':
> +try:
>      import curses
>      import fcntl
>      import termios
> -else:
> +except ImportError:

If demandimport is enabled, these imports won't raise ImportError here.

(I didn't read the patches carefully, so I might be wrong.)