Added function gitflow_require_initialized(), to assert that the gitflow
variables are all set (they need to be set explicitly once).
diff --git a/git-flow-feature b/git-flow-feature
index 701ed6b..d005648 100644
--- a/git-flow-feature
+++ b/git-flow-feature
@@ -13,8 +13,9 @@
 #
 
 gitflow_require_git_repo
+gitflow_require_initialized
 gitflow_load_settings
-PREFIX=$(git config --get gitflow.prefix.feature || echo feature/)
+PREFIX=$(git config --get gitflow.prefix.feature)
 
 usage() {
 	echo "usage: git flow feature [list] [-v]"
diff --git a/git-flow-hotfix b/git-flow-hotfix
index 357eb78..347b811 100644
--- a/git-flow-hotfix
+++ b/git-flow-hotfix
@@ -13,9 +13,10 @@
 #
 
 gitflow_require_git_repo
+gitflow_require_initialized
 gitflow_load_settings
 VERSION_PREFIX=$(git config --get gitflow.prefix.versiontag)
-PREFIX=$(git config --get gitflow.prefix.hotfix || echo hotfix/)
+PREFIX=$(git config --get gitflow.prefix.hotfix)
 
 usage() {
 	echo "usage: git flow hotfix [list] [-v]"
diff --git a/git-flow-release b/git-flow-release
index 38e1790..9aedf3c 100644
--- a/git-flow-release
+++ b/git-flow-release
@@ -13,9 +13,10 @@
 #
 
 gitflow_require_git_repo
+gitflow_require_initialized
 gitflow_load_settings
 VERSION_PREFIX=$(git config --get gitflow.prefix.versiontag)
-PREFIX=$(git config --get gitflow.prefix.release || echo release/)
+PREFIX=$(git config --get gitflow.prefix.release)
 
 usage() {
 	echo "usage: git flow release [list] [-v]"
diff --git a/git-flow-support b/git-flow-support
index 1bdbaed..8a8ac56 100644
--- a/git-flow-support
+++ b/git-flow-support
@@ -13,9 +13,10 @@
 #
 
 gitflow_require_git_repo
+gitflow_require_initialized
 gitflow_load_settings
 VERSION_PREFIX=$(git config --get gitflow.prefix.versiontag)
-PREFIX=$(git config --get gitflow.prefix.support || echo support/)
+PREFIX=$(git config --get gitflow.prefix.support)
 
 warn "note: The support subcommand is still very EXPERIMENTAL!"
 warn "note: DO NOT use it in a production situation."
diff --git a/gitflow-common b/gitflow-common
index 6e5056e..70b137b 100644
--- a/gitflow-common
+++ b/gitflow-common
@@ -74,8 +74,8 @@
 # loading settings that can be overridden using git config
 gitflow_load_settings() {
 	export DOT_GIT_DIR=$(git rev-parse --git-dir >/dev/null 2>&1)
-	export MASTER_BRANCH=$(git config --get gitflow.branch.master || echo master)
-	export DEVELOP_BRANCH=$(git config --get gitflow.branch.develop || echo develop)
+	export MASTER_BRANCH=$(git config --get gitflow.branch.master)
+	export DEVELOP_BRANCH=$(git config --get gitflow.branch.develop)
 	export ORIGIN=$(git config --get gitflow.origin || echo origin)
 }
 
@@ -144,7 +144,13 @@
 
 gitflow_require_git_repo() {
 	if ! git rev-parse --git-dir >/dev/null 2>&1; then
-		die "Not a git repository"
+		die "fatal: Not a git repository"
+	fi
+}
+
+gitflow_require_initialized() {
+	if ! gitflow_is_initialized; then
+		die "fatal: Not a gitflow-enabled repo yet. Please run \"git flow init\" first."
 	fi
 }