Better support for tags in macports

macports/generate-portfile.sh

@@ -8,16 +8,32 @@
 #   This would require a portfile that is based on a tag (e.g. v2.3.0),
 #   optionally including patches, that can be then uploaded to macports
 
-hash=$( git log -1 --format="%h")
+prefix=
+if git describe --exact-match --tags HEAD 2>/dev/null 1>/dev/null
+then
+  version=$(git describe --exact-match --tags HEAD)
+  case "$version" in
+  (v*)
+    version=${version#v}
+    prefix=v
+  esac
+else
+  version=$( git log -1 --format="%h")
+fi
+
+if test -n "$plumed_repository" ; then
+# get this from environment
+  repository="$plumed_repository"
+else
+# parent directory:
+  repository="${PWD%/*}"
+fi
 
 mkdir -p science/plumed
 
-# parent directory:
-repository="${PWD%/*}"
-
 cat Portfile.in |
 sed "
-  s/@_VERSION_@/$hash/
+  s/@_VERSION_@/$version/
   s/@_REVISION_@/0/
 " | awk '{
   if($1=="@_FETCH_@"){
@@ -25,7 +41,7 @@ sed "
     print "git.url             '$repository'"
 # notice that if instead of hashtag we want to put a version, then it should be
 # git.branch          v${version}
-    print "git.branch          ${version}"
+    print "git.branch          '$prefix'${version}"
   } else print
 }'  > science/plumed/Portfile