`nimble setup` adds empty lines to `config.nims`
Running `nimble setup` (multiple times), every time there is some change in `config.nims`, it also adds a new empty line at the top of it.

```diff
--- a/config.nims
+++ b/config.nims
@@ -1,6 +1,8 @@
 
 
+
 # begin Nimble config (version 2)
+--noNimblePath
 when withDir(thisDir(), system.fileExists("nimble.paths")):
   include "nimble.paths"
 # end Nimble config
```

Notice that two empty lines already exist (from previous buggy runs of that command), and now it adds a third empty line.

Removing `nimble.lock` and `nimble.paths` and running `nimble setup` again, produces:

```diff
--- a/config.nims
+++ b/config.nims
@@ -1,5 +1,7 @@
 
 
+
+
 # begin Nimble config (version 2)
 when withDir(thisDir(), system.fileExists("nimble.paths")):
   include "nimble.paths"
```

Now, running `nimble lock` and then `nimble setup` produces:

```diff
--- a/config.nims
+++ b/config.nims
@@ -1,6 +1,10 @@
 
 
+
+
+
 # begin Nimble config (version 2)
+--noNimblePath
 when withDir(thisDir(), system.fileExists("nimble.paths")):
   include "nimble.paths"
 # end Nimble config
```