Merge "Add call trace in error message"

functions

@@ -76,6 +76,19 @@ function cp_it {
 }
 
 
+# Prints backtrace info
+# filename:lineno:function
+function backtrace {
+    local level=$1
+    local deep=$((${#BASH_SOURCE[@]} - 1))
+    echo "[Call Trace]"
+    while [ $level -le $deep ]; do
+        echo "${BASH_SOURCE[$deep]}:${BASH_LINENO[$deep-1]}:${FUNCNAME[$deep-1]}"
+        deep=$((deep - 1))
+    done
+}
+
+
 # Prints line number and "message" then exits
 # die $LINENO "message"
 function die() {
@@ -85,6 +98,7 @@ function die() {
     if [ $exitcode == 0 ]; then
         exitcode=1
     fi
+    backtrace 2
     err $line "$*"
     exit $exitcode
 }