Add filter for tag message.

If a tag message is given, the message can be modified using the filters:
- filter-flow-hotfix-finish-tag-message
- filter-flow-release-finish-tag-message
- filter-flow-release-branch-tag-message

git-flow-hotfix

@@ -349,6 +349,7 @@ b,nobackmerge     Don't back-merge master, or tag if applicable, in develop
 	gitflow_override_flag_string "HOTFIX_FINISH_MESSAGE" "message"
 	gitflow_override_flag_string "HOTFIX_FINISH_MESSAGEFILE" "messagefile"
 
+
 	remotebranchdeleted=$FLAGS_FALSE
 	localbranchdeleted=$FLAGS_FALSE
 	gitflow_require_version_arg
@@ -448,12 +449,16 @@ b,nobackmerge     Don't back-merge master, or tag if applicable, in develop
 			if [ "$FLAGS_message" != "" ] && [ "$FLAGS_messagefile" != "" ]; then
 				die "Use either -m,--message or -f,--messagefile. Can not use both options at the same time"
 			fi
-		opts="-a"
-		flag sign && opts="$opts -s"
-		[ "$FLAGS_signingkey" != "" ] && opts="$opts -u '$FLAGS_signingkey'"
-		[ "$FLAGS_message" != "" ] && opts="$opts -m '$FLAGS_message'"
-		[ "$FLAGS_messagefile" != "" ] && opts="$opts -F '$FLAGS_messagefile'"
-		eval git_do tag $opts "$VERSION_PREFIX$VERSION" || die "Tagging failed. Please run finish again to retry."
+			opts="-a"
+			flag sign && opts="$opts -s"
+			[ "$FLAGS_signingkey" != "" ] && opts="$opts -u '$FLAGS_signingkey'"
+			if [ "$FLAGS_message" != "" ]; then
+				# Run filter on the tag message
+				FLAGS_message=$(run_filter_hook hotfix-finish-tag-message "${FLAGS_message}" "$VERSION_PREFIX$VERSION")
+				opts="$opts -m '$FLAGS_message'"
+			fi
+			[ "$FLAGS_messagefile" != "" ] && opts="$opts -F '$FLAGS_messagefile'"
+			eval git_do tag $opts "$VERSION_PREFIX$VERSION" || die "Tagging failed. Please run finish again to retry."
 		fi
 	fi
 

git-flow-release

@@ -98,7 +98,11 @@ _finish_from_develop() {
 			opts="-a"
 			flag sign && opts="$opts -s"
 			[ "$FLAGS_signingkey" != "" ] && opts="$opts -u '$FLAGS_signingkey'"
-			[ "$FLAGS_message" != "" ] && opts="$opts -m '$FLAGS_message'"
+			if [ "$FLAGS_message" != "" ]; then
+				# Run filter on the tag message
+				FLAGS_message=$(run_filter_hook release-finish-tag-message "${FLAGS_message}" "$VERSION_PREFIX$VERSION")
+				opts="$opts -m '$FLAGS_message'"
+			fi
 			[ "$FLAGS_messagefile" != "" ] && opts="$opts -F '$FLAGS_messagefile'"
 			eval git_do tag $opts "$VERSION_PREFIX$VERSION" || die "Tagging failed. Please run finish again to retry."
 		fi
@@ -265,7 +269,11 @@ _finish_base() {
 			opts="-a"
 			flag sign && opts="$opts -s"
 			[ "$FLAGS_signingkey" != "" ] && opts="$opts -u '$FLAGS_signingkey'"
-			[ "$FLAGS_message" != "" ] && opts="$opts -m '$FLAGS_message'"
+			if [ "$FLAGS_message" != "" ]; then
+				# Run filter on the tag message
+				FLAGS_message=$(run_filter_hook release-finish-tag-message "${FLAGS_message}" "$VERSION_PREFIX$VERSION")
+				opts="$opts -m '$FLAGS_message'"
+			fi
 			[ "$FLAGS_messagefile" != "" ] && opts="$opts -F '$FLAGS_messagefile'"
 			eval git_do tag $opts "$VERSION_PREFIX$VERSION" || die "Tagging failed. Please run finish again to retry."
 		fi
@@ -770,7 +778,11 @@ S,squash 		Squash release during merge
 			opts="-a"
 			flag sign && opts="$opts -s"
 			[ "$FLAGS_signingkey" != "" ] && opts="$opts -u '$FLAGS_signingkey'"
-			[ "$FLAGS_message" != "" ] && opts="$opts -m '$FLAGS_message'"
+			if [ "$FLAGS_message" != "" ]; then
+				# Run filter on the tag message
+				FLAGS_message=$(run_filter_hook release-branch-tag-message "${FLAGS_message}" "$VERSION_PREFIX$VERSION")
+				opts="$opts -m '$FLAGS_message'"
+			fi
 			[ "$FLAGS_messagefile" != "" ] && opts="$opts -F '$FLAGS_messagefile'"
 			eval git_do tag $opts "$VERSION_PREFIX$VERSION" || die "Tagging failed. Please run finish again to retry."
 		fi

hooks/filter-flow-hotfix-finish-tag-message

@@ -0,0 +1,22 @@
+#!/bin/sh
+#
+# Runs during git flow hotfix finish and a tag message is given
+#
+# Positional arguments:
+# $1    Message
+# $2    Full version
+#
+# Return MESSAGE
+#
+# The following variables are available as they are exported by git-flow:
+#
+# MASTER_BRANCH - The branch defined as Master
+# DEVELOP_BRANCH - The branch defined as Develop
+#
+MESSAGE="$1"
+
+# Implement your script here.
+
+# Return the MESSAGE
+echo "${MESSAGE}"
+exit 0

hooks/filter-flow-release-branch-tag-message

@@ -0,0 +1,22 @@
+#!/bin/sh
+#
+# Runs during git flow release branch and a tag message is given
+#
+# Positional arguments:
+# $1    Message
+# $2    Full version
+#
+# Return MESSAGE
+#
+# The following variables are available as they are exported by git-flow:
+#
+# MASTER_BRANCH - The branch defined as Master
+# DEVELOP_BRANCH - The branch defined as Develop
+#
+MESSAGE="$1"
+
+# Implement your script here.
+
+# Return the MESSAGE
+echo "${MESSAGE}"
+exit 0

hooks/filter-flow-release-finish-tag-message

@@ -0,0 +1,22 @@
+#!/bin/sh
+#
+# Runs during git flow release finish and a tag message is given
+#
+# Positional arguments:
+# $1    Message
+# $2    Full version
+#
+# Return MESSAGE
+#
+# The following variables are available as they are exported by git-flow:
+#
+# MASTER_BRANCH - The branch defined as Master
+# DEVELOP_BRANCH - The branch defined as Develop
+#
+MESSAGE="$1"
+
+# Implement your script here.
+
+# Return the MESSAGE
+echo "${MESSAGE}"
+exit 0