Regular `overrideAttrs` also supports passing a plain attribute set.
Before this PR:
```
nix-repl> tmuxPlugins.battery.overrideAttrs { pname = "my-battery"; }
error: attempt to call something which is not a function but a set: {
pname = "my-battery"; }
```
After, it works.
Wolfgang Walther
37fda8bd49