make envvars case-insensitive

pollen/private/cache-utils.rkt

@@ -33,7 +33,7 @@
                    ;; user-designated files to track
                    (map ->string (setup:cache-watchlist source-path)))))
   (define env-rec (for/list ([env-name (in-list (cons default-env-name (sort (setup:envvar-watchlist source-path) bytes<?)))])
-                            (cons env-name (match (getenv env-name)
+                            (cons env-name (match (getenv (string-downcase (->string env-name)))
                                              [#false #false]
                                              [str (string-downcase (->string str))]))))
   (define poly-flag (and (has-inner-poly-ext? source-path) (current-poly-target)))

pollen/private/ts.rktd

@@ -1 +1 @@
-1566501292
+1566501806

pollen/scribblings/setup.scrbl

@@ -125,6 +125,8 @@ If the cache can't find a certain file on the watchlist, no error will arise. Th
 
 @defoverridable[envvar-watchlist (listof string?)]{List of extra environment variables that are used in cache keys. Separate caches will be maintained for each distinct value of an environment variable. @secref["The_POLLEN_environment_variable"] is always used, regardless of how this value is set.
 
+Both the names and the values of environment variables are case-insensitive, so @racket["PUB"] and @racket["pub"] and @racket["pUb"] are all treated the same.
+
 @history[#:added "2.1"]}