fix of http-party#738

lib/http-proxy/common.js

@@ -139,19 +139,28 @@ common.urlJoin = function() {
       lastIndex = args.length - 1,
       last = args[lastIndex],
       lastSegs = last.split('?'),
-      retSegs;
+      retSegs = [];
 
   args[lastIndex] = lastSegs[0];
 
   //
   // Join all strings, but remove empty strings so we don't get extra slashes from
   // joining e.g. ['', 'am']
   //
-  retSegs = [
-    args.filter(function filter(a) {
-      return !!a;
-    }).join('/').replace(/\/+/g, '/')
-  ];
+
+  args.filter(function filter(a) {
+    return !!a;
+  }).forEach(function(v, idx) {
+      if(idx != 0){
+        v = v.replace(/^\//, '');
+      }
+      if(v) {
+
+        retSegs.push(v);
+      }
+    })
+
+  retSegs = [retSegs.join('/')];
 
   // Only join the query string if it exists so we don't have trailing a '?'
   // on every request

test/lib-http-proxy-common-test.js

@@ -209,7 +209,7 @@ describe('lib/http-proxy/common.js', function () {
         target: { path: '/forward' },
       }, { url: '/?foo=bar//&target=http://foobar.com/' });
 
-      expect(outgoing.path).to.eql('/forward/?foo=bar//&target=http://foobar.com/');
+      expect(outgoing.path).to.eql('/forward?foo=bar//&target=http://foobar.com/');
     })
   });