Accepting request 1104190 from home:dimstar:Factory

- xznew: Remove bashsism.
- build: pass CONFIG_SHELL=/bin/sh to configure: the posix tools
  are setting the current SHELL as the shebang, which is overkill:
  any posix compliant shell, aka /bin/sh, is sufficient.

OBS-URL: https://build.opensuse.org/request/show/1104190
OBS-URL: https://build.opensuse.org/package/show/Base:System/xz?expand=0&rev=138

xznew

@@ -52,7 +52,7 @@ if test -z "$cpmod" && ${TOUCH-touch} -r $tmp/1 $tmp/2 2>/dev/null; then
 fi
 
 # check about xz extension
-xz $tmp/1 &> /dev/null
+xz $tmp/1 > /dev/null 2>&1
 ext=`echo $tmp/1* | sed "s|$tmp/1||"`
 rm -rf $tmp/
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