feat(updater): save version prior to updating so `omz changelog` just works™

Fixes #9505

tools/changelog.sh

@@ -340,16 +340,23 @@ function display-release {
 
 function main {
   # $1 = until commit, $2 = since commit
-  # $3 = output format (--raw|--text|--md)
   local until="$1" since="$2"
+
+  # $3 = output format (--text|--raw|--md)
+  # --md:   uses markdown formatting
+  # --raw:  outputs without style
+  # --text: uses ANSI escape codes to style the output
   local output=${${3:-"--text"}#--*}
 
   if [[ -z "$until" ]]; then
     until=HEAD
   fi
 
-  # If $since is not specified, look up first version tag before $until
   if [[ -z "$since" ]]; then
+    # If $since is not specified:
+    # 1) try to find the version used before updating
+    # 2) try to find the first version tag before $until
+    since=$(command git config --get oh-my-zsh.lastVersion 2>/dev/null) || \
     since=$(command git describe --abbrev=0 --tags "$until^" 2>/dev/null) || \
     unset since
   elif [[ "$since" = --all ]]; then

tools/upgrade.sh

@@ -10,7 +10,7 @@ cd "$ZSH"
 # and that terminal supports them.
 
 local -a RAINBOW
-local RED GREEN YELLOW BLUE UNDER BOLD RESET
+local RED GREEN YELLOW BLUE BOLD DIM UNDER RESET
 
 if [ -t 1 ]; then
   RAINBOW=(
@@ -28,6 +28,7 @@ if [ -t 1 ]; then
   YELLOW=$(printf '\033[33m')
   BLUE=$(printf '\033[34m')
   BOLD=$(printf '\033[1m')
+  DIM=$(printf '\033[2m')
   UNDER=$(printf '\033[4m')
   RESET=$(printf '\033[m')
 fi
@@ -69,6 +70,9 @@ if git pull --rebase --stat origin master; then
   else
     message="Hooray! Oh My Zsh has been updated!"
 
+    # Save the commit prior to updating
+    git config oh-my-zsh.lastVersion "$last_commit"
+
     # Display changelog with less if available, otherwise just print it to the terminal
     if [[ "$1" = --interactive ]]; then
       if (( $+commands[less] )); then
@@ -77,6 +81,8 @@ if git pull --rebase --stat origin master; then
         "$ZSH/tools/changelog.sh" HEAD "$last_commit"
       fi
     fi
+
+    printf "${BLUE}%s \`${BOLD}%s${RESET}${BLUE}\`${RESET}\n" "You can see the changelog again with" "omz changelog"
   fi
 
   printf '%s         %s__      %s           %s        %s       %s     %s__   %s\n' $RAINBOW $RESET