Speedup VCS segment

Now the untracked files are detected via `git ls-files`, which is
much faster than `git status`. Additionally, we flipped the default
for checking submodules. They are now NOT checked by default, as most
users probably do not use git submodules.

functions/vcs.zsh

@@ -6,18 +6,12 @@
 # https://github.com/bhilburn/powerlevel9k
 ################################################################
 
-set_default POWERLEVEL9K_VCS_SHOW_SUBMODULE_DIRTY true
+set_default POWERLEVEL9K_VCS_SHOW_SUBMODULE_DIRTY false
 function +vi-git-untracked() {
-    # TODO: check git >= 1.7.2 - see function git_compare_version()
-    local FLAGS
-    FLAGS=('--porcelain')
-
-    if [[ "$POWERLEVEL9K_VCS_SHOW_SUBMODULE_DIRTY" == "false" ]]; then
-      FLAGS+='--ignore-submodules=dirty'
-    fi
-
-    if [[ $(command git rev-parse --is-inside-work-tree 2> /dev/null) == 'true' && \
-            -n $(command git status ${FLAGS} | \grep -E '^\?\?' 2> /dev/null | tail -n1) ]]; then
+    if [[ "$POWERLEVEL9K_VCS_SHOW_SUBMODULE_DIRTY" == "true" && "$(command git submodule foreach 'git ls-files --others --exclude-standard')" != "" ]]; then
+        hook_com[unstaged]+=" $(print_icon 'VCS_UNTRACKED_ICON')"
+        VCS_WORKDIR_HALF_DIRTY=true
+    elif [[ "$(command git ls-files --others --exclude-standard)" != "" ]]; then
         hook_com[unstaged]+=" $(print_icon 'VCS_UNTRACKED_ICON')"
         VCS_WORKDIR_HALF_DIRTY=true
     else

test/segments/vcs-git.spec

@@ -375,4 +375,29 @@ function testShorteningCommitHashIsNotShownIfShowChangesetIsFalse() {
   assertEquals "%K{002} %F{000} master %k%F{002}%f " "$(build_left_prompt)"
 }
 
+function testDetectingUntrackedFilesInSubmodulesWork() {
+  local -a POWERLEVEL9K_LEFT_PROMPT_ELEMENTS
+  POWERLEVEL9K_LEFT_PROMPT_ELEMENTS=(vcs)
+  local POWERLEVEL9K_VCS_SHOW_SUBMODULE_DIRTY="true"
+  unset POWERLEVEL9K_VCS_UNTRACKED_BACKGROUND
+
+  mkdir ../submodule
+  cd ../submodule
+  git init 1>/dev/null
+  touch "i-am-tracked.txt"
+  git add . 1>/dev/null && git commit -m "Initial Commit" 1>/dev/null
+  # Create untracked file
+  touch "i-am-untracked.txt"
+
+  local submodulePath="${PWD}"
+
+  cd -
+  git submodule add "${submodulePath}" 2>/dev/null
+  git commit -m "Add submodule" 1>/dev/null
+
+  source ${P9K_HOME}/powerlevel9k.zsh-theme
+
+  assertEquals "%K{002} %F{000} master ? %k%F{002}%f " "$(build_left_prompt)"
+}
+
 source shunit2/shunit2