Resolve compatibility issue with Git 2.4

Git 2.4 (once again!) changes output when current state is a detached
branch, it is now:

* (HEAD detached at arc-2014.12)

This patch adds support for this new format as well. Has been reported as
Issue #60.

Signed-off-by: Anton Kolesov <[email protected]>

Author: anthony-kolesov

arc-versions.sh

@@ -156,9 +156,11 @@ do
     then
 	# Only update to latest if we are not in detached HEAD mode.
 	# If tree is in detahed state, output differs between Git versions:
-	# Git 1.8 prints: * (detached from <tag_name>>)
+	# Git >=2.4 prints: *(HEAD detached at <tag_name>)
+	# Git 1.8-2.3 prints: * (detached from <tag_name>)
 	# Git <1.8 prints: * (no branch)
-	if ! git branch | grep -q -e '\* (detached from .*)' -e '\* (no branch)'
+	if ! git branch | grep -q -e '\* (HEAD detached at .*)' \
+	    -e '\* (detached from .*)' -e '\* (no branch)'
 	then
 	    echo "  pulling latest version"
 	    if ! git pull