do's inside top level do's are 'flattened'

gistfile1.clj

;; In a fresh Clojure 1.5.1 'lein repl'

;; clojure.edn is not loaded yet
user=> (clojure.edn/read-string "(5)")

ClassNotFoundException clojure.edn  java.net.URLClassLoader$1.run (URLClassLoader.java:366)

;; trying to eval this form does not do it, because it fails to analyze as a whole
user=> (eval `(when true (require 'clojure.edn) (clojure.edn/read-string "(5)")))

CompilerException java.lang.ClassNotFoundException: clojure.edn, compiling:(/private/var/folders/n5/pypfx1x96gjgzzdhp0jkxl580000gn/T/form-init1598985253681557129.clj:1:1) 

;; Putting it in a do lets each subform be analyzed and evaluated before the next
user=> (eval `(do (require 'clojure.edn) (clojure.edn/read-string "(5)")))
(5)

;; Now clojure.edn is loaded
user=> (clojure.edn/read-string "(5)")
(5)



;;;;;;;;

;; Start over with a fresh 'lein repl' that does not have clojure.edn loaded yet

user=> (clojure.edn/read-string "(5)")

ClassNotFoundException clojure.edn  java.net.URLClassLoader$1.run (URLClassLoader.java:366)

;; Now do the require in a do that is inside of a top level do.  Still works.
user=> (eval `(do (println "hi") (do (require 'clojure.edn) (clojure.edn/read-string "(5)"))))
hi
(5)

user=> (clojure.edn/read-string "(5)")
(5)


;;;;;;;;

;; Start over with a fresh 'lein repl' that does not have clojure.edn loaded yet to check
;; that you can nest it multiple levels deep.  You can.

user=> (clojure.edn/read-string "(5)")

ClassNotFoundException clojure.edn  java.net.URLClassLoader$1.run (URLClassLoader.java:366)
user=> (eval `(do (println "hi") (do (println "there") (do (require 'clojure.edn) (clojure.edn/read-string "(5)")))))
hi
there
(5)
user=> (clojure.edn/read-string "(5)")
(5)

;; Link to portion of Clojure compiler source code that handles this:
;; https://github.com/clojure/clojure/blob/master/src/jvm/clojure/lang/Compiler.java#L5733