lib: stop detecting git versions prior to 1.7.2

The 1.7.2 release was published in July 2010 [1]. It's about time to stop
supporting older versions.

Fixes #4583

[1] https://github.com/git/git/releases/tag/v1.7.2

lib/git.zsh

@@ -10,13 +10,10 @@ function git_prompt_info() {
 
 # Checks if working tree is dirty
 function parse_git_dirty() {
-  local STATUS=''
+  local STATUS
   local -a FLAGS
-  FLAGS=('--porcelain')
+  FLAGS=('--porcelain' '--ignore-submodules=dirty')
   if [[ "$(command git config --get oh-my-zsh.hide-dirty)" != "1" ]]; then
-    if [[ $POST_1_7_2_GIT -gt 0 ]]; then
-      FLAGS+='--ignore-submodules=dirty'
-    fi
     if [[ "$DISABLE_UNTRACKED_FILES_DIRTY" == "true" ]]; then
       FLAGS+='--untracked-files=no'
     fi
@@ -181,28 +178,6 @@ function git_prompt_status() {
   echo $STATUS
 }
 
-# Compares the provided version of git to the version installed and on path
-# Outputs -1, 0, or 1 if the installed version is less than, equal to, or
-# greater than the input version, respectively.
-function git_compare_version() {
-  local INPUT_GIT_VERSION INSTALLED_GIT_VERSION i
-  INPUT_GIT_VERSION=(${(s/./)1})
-  INSTALLED_GIT_VERSION=($(command git --version 2>/dev/null))
-  INSTALLED_GIT_VERSION=(${(s/./)INSTALLED_GIT_VERSION[3]})
-
-  for i in {1..3}; do
-    if [[ $INSTALLED_GIT_VERSION[$i] -gt $INPUT_GIT_VERSION[$i] ]]; then
-      echo 1
-      return 0
-    fi
-    if [[ $INSTALLED_GIT_VERSION[$i] -lt $INPUT_GIT_VERSION[$i] ]]; then
-      echo -1
-      return 0
-    fi
-  done
-  echo 0
-}
-
 # Outputs the name of the current user
 # Usage example: $(git_current_user_name)
 function git_current_user_name() {
@@ -214,8 +189,3 @@ function git_current_user_name() {
 function git_current_user_email() {
   command git config user.email 2>/dev/null
 }
-
-# This is unlikely to change so make it all statically assigned
-POST_1_7_2_GIT=$(git_compare_version "1.7.2")
-# Clean up the namespace slightly by removing the checker function
-unfunction git_compare_version