Fix race condition in sync tests (#280)

The nightly and release tests could step on each other. Both could
be running at the same time and could be executing the symlink update
in an interleaved fashion.

We now do nightly and release sync tests in different asset directories
to have them avoid stepping on one another.

Fixes #279

test/main.pony

@@ -15,7 +15,9 @@ actor Main is TestList
   fun tag tests(test: PonyTest) =>
     test(_TestParsePlatform)
     for package in Packages().values() do
-      test(_TestSync(package))
+      for channel in ["nightly"; "release"].values() do
+        test(_TestSync(package, channel))
+      end
     end
     test(_TestSelect)
 
@@ -63,15 +65,17 @@ class _TestParsePlatform is UnitTest
 
 class _TestSync is UnitTest
   let _pkg_name: String
+  let _channel: String
 
-  new iso create(pkg_name: String) =>
+  new iso create(pkg_name: String, channel: String) =>
     _pkg_name = pkg_name
+    _channel = channel
 
   fun name(): String =>
-    "sync - " + _pkg_name
+    "sync - " + _pkg_name + "-" + _channel
 
   fun apply(h: TestHelper) =>
-    _SyncTester(h, h.env.root, _pkg_name)
+    _SyncTester(h, h.env.root, _pkg_name, _channel)
     h.long_test(120_000_000_000)
 
 class _TestSelect is UnitTest
@@ -157,28 +161,31 @@ actor _SyncTester is PonyupNotify
   let _pkg_name: String
   embed _pkgs: Array[Package] = []
 
-  new create(h: TestHelper, auth: AmbientAuth, pkg_name: String) =>
+  new create(
+    h: TestHelper,
+    auth: AmbientAuth,
+    pkg_name: String,
+    channel: String)
+  =>
     _h = h
     _auth = auth
     _pkg_name = pkg_name
 
     let platform = _TestPonyup.platform(h)
     let http_get = HTTPGet(NetAuth(_auth), this)
-    for channel in ["nightly"; "release"].values() do
-      try
-        let pkg = Packages.from_fragments(
-          _pkg_name, channel, "latest", platform.split("-"))?
-        let query_string: String =
-          Cloudsmith.repo_url(channel).clone()
-            .> append(Cloudsmith.query(pkg))
-            .> replace("page_size=1", "page_size=2")
-        log(Extra, "query url: " + query_string)
-        http_get(
-          query_string,
-          {(_)(self = recover tag this end, pkg) =>
-            QueryHandler(self, {(res) => self.add_packages(pkg, consume res) })
-          })
-      end
+    try
+      let pkg = Packages.from_fragments(
+        _pkg_name, channel, "latest", platform.split("-"))?
+      let query_string: String =
+        Cloudsmith.repo_url(channel).clone()
+          .> append(Cloudsmith.query(pkg))
+          .> replace("page_size=1", "page_size=2")
+      log(Extra, "query url: " + query_string)
+      http_get(
+        query_string,
+        {(_)(self = recover tag this end, pkg) =>
+          QueryHandler(self, {(res) => self.add_packages(pkg, consume res) })
+        })
     end
 
   be add_packages(pkg: Package, res: Array[JsonObject val] iso) =>
@@ -197,15 +204,16 @@ actor _SyncTester is PonyupNotify
     end
     try
       let pkg = _pkgs.shift()?
-      _h.env.out.print("sync -- " + pkg.string())
+      let name_with_channel = recover val pkg.name + "/" + pkg.channel end
+      _h.env.out.print("sync -- " + name_with_channel)
       _TestPonyup.exec(
         _h,
-        pkg.name,
+        name_with_channel,
         [ "update"; pkg.name; pkg.channel + "-" + pkg.version
           "--platform=" + pkg.platform()
         ],
         {()(self = recover tag this end)? =>
-          _TestPonyup.check_files(_h, pkg.name, pkg)?
+          _TestPonyup.check_files(_h, name_with_channel, pkg)?
           self.run()
         } val)?
     else