Optimize the detection of the Linux distro using lsb_release.

* Use a `case` statement for additional future checks.
* Prefer checking `lsb_release -i` (Distributor ID) instead of
  `lsb_release -c` (codename).

Author: postmodern

share/ruby-install/system.sh

@@ -49,10 +49,12 @@ function detect_package_manager()
 				if command -v pacman >/dev/null; then
 					package_manager="pacman"
 				fi
-			elif [[ -x /bin/lsb_release ]] && lsb_release -c|grep -q void; then
-				if command -v xbps-install >/dev/null; then
-					package_manager="xbps"
-				fi
+			elif command -v lsb_release 2>/dev/null; then
+				case "$(lsb_release -i)" in
+					*VoidLinux*)
+						package_manager="xbps"
+						;;
+				esac
 			fi
 			;;
 		Darwin)

test/system-tests/detect_package_manager_test.sh

@@ -44,7 +44,7 @@ function test_detect_package_manager_on_open_suse_systems_with_zypper()
 
 function test_detect_package_manager_on_void_systems_with_xbps()
 {
-	command -v lsb_release >/dev/null &&
+	[[ "$(lsb_release -i 2>/dev/null)" == *VoidLinux* ]] &&
 		command -v xbps-install >/dev/null || return 0
 
 	assertEquals "did not detect xbps-install" "xbps" "$package_manager"