Sometimes is useful to have a different firmware/program name in build_dir.
platformio.ini:
[env:env_custom_prog_name]
platform = espressif8266
board = nodemcuv2
framework = arduino
build_flags = -D VERSION=13
extra_scripts = pre:extra_script.py
extra_script.py:
Import("env")
my_flags = env.ParseFlags(env['BUILD_FLAGS'])
defines = {k: v for (k, v) in my_flags.get("CPPDEFINES")}
# print(defines)
env.Replace(PROGNAME="firmware_%s" % defines.get("VERSION"))