Turn off tracing when outputting errors

When outputting these error strings, turn off the tracing so the user
can actually read it.  Also reword the "not root" user message so it
fits into a standard terminal window length.

Change-Id: I466c60865bc1128f4edd219f831a9c6cffa67829
Parital-Bug: #1517199

stack.sh

@@ -75,6 +75,7 @@ fi
 
 # Check if run in POSIX shell
 if [[ "${POSIXLY_CORRECT}" == "y" ]]; then
+    set +o xtrace
     echo "You are running POSIX compatibility mode, DevStack requires bash 4.2 or newer."
     exit 1
 fi
@@ -85,11 +86,11 @@ fi
 # action to create a suitable user account.
 
 if [[ $EUID -eq 0 ]]; then
-    echo "You are running this script as root."
-    echo "Cut it out."
-    echo "Really."
-    echo "If you need an account to run DevStack, do this (as root, heh) to create a non-root account:"
-    echo "$TOP_DIR/tools/create-stack-user.sh"
+    set +o xtrace
+    echo "DevStack should be run as a user with sudo permissions, "
+    echo "not root."
+    echo "A \"stack\" user configured correctly can be created with:"
+    echo " $TOP_DIR/tools/create-stack-user.sh"
     exit 1
 fi
 
@@ -98,6 +99,7 @@ fi
 # virtual env, and will fail in really odd ways if you do this. Make
 # this explicit as it has come up on the mailing list.
 if [[ -n "$VIRTUAL_ENV" ]]; then
+    set +o xtrace
     echo "You appear to be running under a python virtualenv."
     echo "DevStack does not support this, as we may break the"
     echo "virtualenv you are currently in by modifying "
@@ -111,6 +113,7 @@ fi
 # on a lot of different environments, you sometimes run it on the
 # wrong box. This makes there be a way to prevent that.
 if [[ -e $HOME/.no-devstack ]]; then
+    set +o xtrace
     echo "You've marked this host as a no-devstack host, to save yourself from"
     echo "running devstack accidentally. If this is in error, please remove the"
     echo "~/.no-devstack file"