Commit 9a5b5d9fe8 added Haskell
dependencies (GHC and packages) to the xmonad binary's environment even
if xmonad had been preconfigured (via the "config" option). The intent
was to enable one-off recompiling using a local config file (e.g.
~/.config/xmonad/xmonad.hs), so the user can get quick feedback while
developing their config.
While this works, it may not be a common use-case, and it requires some
careful crafting in xmonad.hs itself. On top of that, it significantly
increases the size of the closure.
Given all that, commit b69d9d3c23 removed
GHC and packages from the binary's environment.
But there are still those among us who want to be able to recompile from
a preconfigured xmonad, so let's provide a way to opt-into configured
recompilation.
a3ea1bc599