Fix for /etc/profile.d/prompt.sh

Prod-Related: PROD-34351
Change-Id: I17737dcc73f5fc685b0519c2350db123eb64c6d6
diff --git a/linux/files/prompt.sh b/linux/files/prompt.sh
index 27061d1..0f74fef 100644
--- a/linux/files/prompt.sh
+++ b/linux/files/prompt.sh
@@ -1,5 +1,4 @@
-{%- from "linux/map.jinja" import system with context %}
-
+{%- from "linux/map.jinja" import system with context -%}
 # Don't set special prompt when not using Bash or ZSH
 [ -n "$BASH_VERSION" -o -n "$ZSH_VERSION" ] || return 0
 
@@ -7,14 +6,15 @@
 [[ $- == *i* ]] || return 0
 
 {%- for user, prompt in system.prompt.items() %}
-{% if user != "default" %}
-if [ "$USERNAME" == "{{ user }}" ]; then
-  export PS1="{{ prompt }} "
-  return 0
+  {%- if user != "default" %}
+if $(id -u {{ user }} >/dev/null 2>&1); then
+  if [ $(id -u) -eq $(id -u {{ user }}) ]; then
+    export PS1="{{ prompt }} "
+    return 0
+  fi
 fi
-{% endif %}
+  {%- endif %}
 {%- endfor %}
-
-{% if system.prompt.default is defined %}
+{%- if system.prompt.default is defined %}
 export PS1="{{ system.prompt.default }} "
 {%- endif %}