Upstream unsets only NODE_PATH:

... but not NIX_LDFLAGS.

With a large number of deps, these env vars (NODE_PATH and NIX_LDFLAGS) can grow quite large (>128k), such that leaving them exported and attempting to invoke shell commands can lead to misleading "Argument list too long" errors, which actually indicate that kernel-limited env space has been exceeded.

We patch nixfromnpm to unset NIX_LDFLAGS but we think a better solution would instead use something like passAsFile instead of exporting the environment variables.