Have version.sh check for version information in EXPORTED_VERSION

(formerly GITHASH).

This gives us usable version information for source which has been
exported from git with git archive.

.gitattributes

@@ -1,2 +1,2 @@
-mythtv/GITHASH export-subst
-mythplugins/GITHASH export-subst
+mythtv/EXPORTED_VERSION export-subst
+mythplugins/EXPORTED_VERSION export-subst

mythtv/EXPORTED_VERSION

@@ -0,0 +1,2 @@
+SOURCE_VERSION="$Format:%h$"
+BRANCH="$Format:%d$"

mythtv/version.sh

@@ -27,12 +27,16 @@ SOURCE_VERSION=$(git describe --dirty || git describe || echo Unknown)
 
 case "${SOURCE_VERSION}" in
     exported|Unknown)
-        if test -e $GITTREEDIR/VERSION ; then
+        if ! grep -q Format $GITTREEDIR/EXPORTED_VERSION; then
+            . $GITTREEDIR/EXPORTED_VERSION
+        elif test -e $GITTREEDIR/VERSION ; then
             . $GITTREEDIR/VERSION
         fi
     ;;
     *)
-    BRANCH=$(git branch --no-color | sed -e '/^[^\*]/d' -e 's/^\* //' -e 's/(no branch)/exported/')
+        if [ -z "${BRANCH}" ]; then
+            BRANCH=$(git branch --no-color | sed -e '/^[^\*]/d' -e 's/^\* //' -e 's/(no branch)/exported/')
+        fi
     ;;
 esac