Improve conan copy UX (#7741)

* #7736 Improve conan copy UX

Signed-off-by: Uilian Ries <uilianries@gmail.com>

* Fix reference counter for conan copy

Signed-off-by: Uilian Ries <uilianries@gmail.com>

conans/client/cmd/copy.py

@@ -31,9 +31,12 @@ def cmd_copy(ref, user_channel, package_ids, cache, user_io, remote_manager, loa
 
 def package_copy(src_ref, user_channel, package_ids, cache, user_io, short_paths=False,
                  force=False):
-    dest_ref = ConanFileReference.loads("%s/%s@%s" % (src_ref.name,
-                                                      src_ref.version,
-                                                      user_channel))
+
+    ref = "%s/%s@%s" % (src_ref.name, src_ref.version, user_channel)
+    if ref.count('@') > 1:
+        raise ConanException("Destination must contain user/channel only.")
+
+    dest_ref = ConanFileReference.loads(ref)
     # Generate metadata
     src_layout = cache.package_layout(src_ref, short_paths)
     src_metadata = src_layout.load_metadata()

conans/test/functional/command/copy_test.py

@@ -1,5 +1,6 @@
 import os
 import unittest
+import textwrap
 
 from conans.model.ref import ConanFileReference
 from conans.test.utils.tools import TestClient, TestServer
@@ -102,3 +103,15 @@ def test_copy_with_p_and_all(self):
         client.run("copy pkg/0.1@user/channel other/channel -p {} --all".format("mimic"),
                    assert_error=True)
         self.assertIn("Cannot specify both --all and --package", client.out)
+
+    def test_copy_full_reference(self):
+        conanfile = textwrap.dedent("""
+            from conans import ConanFile
+            class Pkg(ConanFile):
+                settings = "os"
+        """)
+        client = TestClient()
+        client.save({"conanfile.py": conanfile})
+        client.run("export . pkg/0.1@user/channel")
+        client.run("copy pkg/0.1@user/channel pkg/0.1@other/branch", assert_error=True)
+        self.assertIn("Destination must contain user/channel only.", client.out)