should probably use the value of CASE_INSENSITIVE

lib/completion.zsh

@@ -14,7 +14,7 @@ compinit
 zmodload -i zsh/complist
 
 ## case-insensitive (all),partial-word and then substring completion
-if [ "$CASE_SENSITIVE" ]; then
+if [ "x$CASE_SENSITIVE" = "xtrue" ]; then
   zstyle ':completion:*' matcher-list 'r:|[._-]=* r:|=*' 'l:|=* r:|=*'
   unset CASE_SENSITIVE
 else
@@ -42,4 +42,4 @@ zstyle ':completion:*:*:(ssh|scp):*:*' hosts `sed 's/^\([^ ,]*\).*$/\1/' ~/.ssh/
 # zstyle ':completion:*:history-words' stop yes
 # zstyle ':completion:*:history-words' remove-all-dups yes
 # zstyle ':completion:*:history-words' list false
-# zstyle ':completion:*:history-words' menu yes
\ No newline at end of file
+# zstyle ':completion:*:history-words' menu yes