[gnome-terminal] build: Use portable shell in configure.ac

[Egmont Koblinger <egmontkob src gnome org>]

commit 5bb8fececb0392e548ecbf6434b5c7d898d153d9
Author: Alexander Tsoy <alexander tsoy me>
Date:   Tue Dec 2 20:15:45 2014 +0300

    build: Use portable shell in configure.ac

 configure.ac |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 68c957f..9d394dc 100644
--- a/configure.ac
+++ b/configure.ac
@@ -246,7 +246,7 @@ AM_CONDITIONAL([WITH_NAUTILUS_EXTENSION],[test "$with_nautilus_extension" = "yes
 # **********************
 
 if test -f /etc/os-release; then
-  DISTRO="$(source /etc/os-release && echo $ID)"
+  DISTRO="$(. /etc/os-release && echo $ID)"
 else
   DISTRO="unknown"
 fi