Windows Batch reads simple.ini and sets environment variables

sample.ini

keya=valuea
keyb=%keya%-withb

sample_output.txt

[ENV] 'keya' = 'valuea'
[ENV] 'keyb' = 'valuea-withb' (expanded from '%keya%-withb')

setfromini.cmd

@echo off
setlocal EnableDelayedExpansion

rem http://stackoverflow.com/questions/25324354/windows-batch-files-what-is-variable-expansion-and-what-does-enabledelayedexpa
rem http://stackoverflow.com/questions/10558316/example-of-delayed-expansion-in-batch-file

set file=%~1

for /f "usebackq delims=" %%a in ("!file!") do (
	set ln=%%a
	for /f "tokens=1,2 delims==" %%b in ("!ln!") do (
		set currkey=%%b
		set currval=%%c
		
		rem echo '!currkey!' with '!currval!'
		for /f "delims=" %%a in ('echo !currval!') do (
			set "!currkey!=%%a"
			if "!currval!" == "%%a" (
				echo [ENV] '!currkey!' = '%%a'
			) else (
				echo [ENV] '!currkey!' = '%%a' (expanded from '!currval!')
			)
			rem echo new value of '!currkey!' is '%%a'
		)
	)
)

endlocal