change the semantics of POWERLEVEL9K_DIR_OMIT_FIRST_CHARACTER to something useful

If POWERLEVEL9K_DIR_OMIT_FIRST_CHARACTER is set to true, it'll remove the leading
slash from the current directory if it's absolute. It will no longer do anything
if the directory is not absolute or if the leading character has been removed
or changed by the shortener.

internal/p10k.zsh

@@ -1915,8 +1915,9 @@ prompt_dir() {
       (( expand )) && _p9k_escape $_POWERLEVEL9K_HOME_FOLDER_ABBREVIATION || _p9k__ret=$_POWERLEVEL9K_HOME_FOLDER_ABBREVIATION
       parts[1]=$_p9k__ret
       [[ $_p9k__ret == *%* ]] && parts[1]+=$style
+    elif [[ $_POWERLEVEL9K_DIR_OMIT_FIRST_CHARACTER == 1 && $fake_first == 0 && $#parts > 1 && -z $parts[1] && -n $parts[2] ]]; then
+      parts[1]=()
     fi
-    [[ $_POWERLEVEL9K_DIR_OMIT_FIRST_CHARACTER == 1 && $#parts > 1 && -n $parts[2] ]] && parts[1]=()
 
     local last_style=
     (( _POWERLEVEL9K_DIR_PATH_HIGHLIGHT_BOLD )) && last_style+=%B
@@ -7422,7 +7423,7 @@ _p9k_must_init() {
     [[ $sig == $_p9k__param_sig ]] && return 1
     _p9k_deinit
   fi
-  _p9k__param_pat=$'v66\1'${ZSH_VERSION}$'\1'${ZSH_PATCHLEVEL}$'\1'
+  _p9k__param_pat=$'v67\1'${ZSH_VERSION}$'\1'${ZSH_PATCHLEVEL}$'\1'
   _p9k__param_pat+=$'${#parameters[(I)POWERLEVEL9K_*]}\1${(%):-%n%#}\1$GITSTATUS_LOG_LEVEL\1'
   _p9k__param_pat+=$'$GITSTATUS_ENABLE_LOGGING\1$GITSTATUS_DAEMON\1$GITSTATUS_NUM_THREADS\1'
   _p9k__param_pat+=$'$DEFAULT_USER\1${ZLE_RPROMPT_INDENT:-1}\1$P9K_SSH\1$__p9k_ksh_arrays'