status: add option for support pipes

Added new option (POWERLEVEL9K_STATUS_SHOW_PIPESTATUS) that shows
the status for all piped commands, not just the right-most.

Closes #514

README.md

@@ -463,6 +463,7 @@ This segment shows the return code of the last command.
 |----------|---------------|-------------|
 |`POWERLEVEL9K_STATUS_VERBOSE`|`true`|Set to false if you wish to not show the error code when the last command returned an error and optionally hide this segment when the last command completed successfully by setting `POWERLEVEL9K_STATUS_OK_IN_NON_VERBOSE` to false.|
 |`POWERLEVEL9K_STATUS_OK_IN_NON_VERBOSE`|`false`|Set to true if you wish to show this segment when the last command completed successfully in non-verbose mode.|
+|`POWERLEVEL9K_STATUS_SHOW_PIPESTATUS`|`false`|Set to true if you wish to show the exit status for all piped commands.|
 
 ##### ram
 

powerlevel9k.zsh-theme

@@ -1019,10 +1019,30 @@ prompt_ssh() {
 # Status: return code if verbose, otherwise just an icon if an error occurred
 set_default POWERLEVEL9K_STATUS_VERBOSE true
 set_default POWERLEVEL9K_STATUS_OK_IN_NON_VERBOSE false
+set_default POWERLEVEL9K_STATUS_SHOW_PIPESTATUS false
 prompt_status() {
-  if [[ "$RETVAL" -ne 0 ]]; then
+  local ec_text
+  local ec_sum
+  local ec
+
+  if [[ $POWERLEVEL9K_STATUS_SHOW_PIPESTATUS == true ]]; then
+    ec_text=${RETVALS[1]}
+    ec_sum=${RETVALS[1]}
+
+    for ec in "${(@)RETVALS[2,-1]}"; do
+      ec_text="${ec_text}|${ec}"
+      ec_sum=$(( $ec_sum + $ec ))
+    done
+  else
+    # We use RETVAL instead of the right-most RETVALS item because
+    # PIPE_FAIL may be set.
+    ec_text=${RETVAL}
+    ec_sum=${RETVAL}
+  fi
+
+  if (( ec_sum > 0 )); then
     if [[ "$POWERLEVEL9K_STATUS_VERBOSE" == true ]]; then
-      "$1_prompt_segment" "$0_ERROR" "$2" "red" "226" "$RETVAL" 'CARRIAGE_RETURN_ICON'
+      "$1_prompt_segment" "$0_ERROR" "$2" "red" "226" "$ec_text" 'CARRIAGE_RETURN_ICON'
     else
       "$1_prompt_segment" "$0_ERROR" "$2" "$DEFAULT_COLOR" "red" "" 'FAIL_ICON'
     fi
@@ -1306,6 +1326,7 @@ powerlevel9k_preexec() {
 set_default POWERLEVEL9K_PROMPT_ADD_NEWLINE false
 powerlevel9k_prepare_prompts() {
   RETVAL=$?
+  RETVALS=( "$pipestatus[@]" )
 
   _P9K_COMMAND_DURATION=$((EPOCHREALTIME - _P9K_TIMER_START))