Add match for `MM` (result of `git commit -p` on a single changed file) to git_prompt_status (#3632)

lib/git.zsh

@@ -141,11 +141,15 @@ function git_prompt_status() {
     STATUS="$ZSH_THEME_GIT_PROMPT_ADDED$STATUS"
   elif $(echo "$INDEX" | grep '^M  ' &> /dev/null); then
     STATUS="$ZSH_THEME_GIT_PROMPT_ADDED$STATUS"
+  elif $(echo "$INDEX" | grep '^MM ' &> /dev/null); then
+    STATUS="$ZSH_THEME_GIT_PROMPT_ADDED$STATUS"
   fi
   if $(echo "$INDEX" | grep '^ M ' &> /dev/null); then
     STATUS="$ZSH_THEME_GIT_PROMPT_MODIFIED$STATUS"
   elif $(echo "$INDEX" | grep '^AM ' &> /dev/null); then
     STATUS="$ZSH_THEME_GIT_PROMPT_MODIFIED$STATUS"
+  elif $(echo "$INDEX" | grep '^MM ' &> /dev/null); then
+    STATUS="$ZSH_THEME_GIT_PROMPT_MODIFIED$STATUS"
   elif $(echo "$INDEX" | grep '^ T ' &> /dev/null); then
     STATUS="$ZSH_THEME_GIT_PROMPT_MODIFIED$STATUS"
   fi