config: only create config dir before write

This change fixes the bug that creates
unnecessary ./etc folder when calling npm
with the --prefix flag.

PR-URL: npm/npm#20212
Credit: @buddydvd
Reviewed-By: @iarna
Fixes: #17322

lib/config.js

@@ -10,6 +10,8 @@ var types = npmconf.defs.types
 var ini = require('ini')
 var editor = require('editor')
 var os = require('os')
+var path = require('path')
+var mkdirp = require('mkdirp')
 var umask = require('./utils/umask')
 var usage = require('./utils/usage')
 var output = require('./utils/output')
@@ -114,14 +116,17 @@ function edit (cb) {
       }, []))
         .concat([''])
         .join(os.EOL)
-      writeFileAtomic(
-        f,
-        data,
-        function (er) {
-          if (er) return cb(er)
-          editor(f, { editor: e }, noProgressTillDone(cb))
-        }
-      )
+      mkdirp(path.dirname(f), function (er) {
+        if (er) return cb(er)
+        writeFileAtomic(
+          f,
+          data,
+          function (er) {
+            if (er) return cb(er)
+            editor(f, { editor: e }, noProgressTillDone(cb))
+          }
+        )
+      })
     })
   })
 }

lib/config/core.js

@@ -155,17 +155,10 @@ function load_ (builtin, rc, cli, cb) {
     // annoying humans and their expectations!
     if (conf.get('prefix')) {
       var etc = path.resolve(conf.get('prefix'), 'etc')
-      mkdirp(etc, function () {
-        defaults.globalconfig = path.resolve(etc, 'npmrc')
-        defaults.globalignorefile = path.resolve(etc, 'npmignore')
-        afterUserContinuation()
-      })
-    } else {
-      afterUserContinuation()
+      defaults.globalconfig = path.resolve(etc, 'npmrc')
+      defaults.globalignorefile = path.resolve(etc, 'npmignore')
     }
-  }
 
-  function afterUserContinuation () {
     conf.addFile(conf.get('globalconfig'), 'global')
 
     // move the builtin into the conf stack now.