disable multiple instantiations.

lib/bitcoind.js

@@ -24,6 +24,11 @@ function Bitcoin(options) {
     return new Bitcoin(options);
   }
 
+  if (Object.keys(this.instances).length) {
+    throw new
+      Error('bitcoind.js cannot be instantiated more than once.');
+  }
+
   EventEmitter.call(this);
 
   this.options = options || {};
@@ -46,12 +51,6 @@ function Bitcoin(options) {
 
   this.config = this.options.datadir + '/bitcoin.conf';
 
-  if (this.instances[this.options.datadir]) {
-    throw new Error(''
-      + 'bitcoind.js cannot be instantiated'
-      + ' more than once on the same datadir.');
-  }
-
   if (!fs.existsSync(this.options.datadir)) {
     mkdirp.sync(this.options.datadir);
   }
@@ -98,7 +97,7 @@ Bitcoin.instances = {};
 Bitcoin.prototype.instances = Bitcoin.instances;
 
 Bitcoin.__defineGetter__('global', function() {
-  return Bitcoin.instances[process.env.HOME + '/.bitcoin'];
+  return Bitcoin.instances[Object.keys(Bitcoin.instances)[0]];
 });
 
 Bitcoin.prototype.start = function(options, callback) {