buildcache list: do not display duplicate specs (#13758)

fixes #13757

lib/spack/spack/cmd/buildcache.py

@@ -416,11 +416,9 @@ def listspecs(args):
     """list binary packages available from mirrors"""
     specs = bindist.get_specs(args.force)
     if args.packages:
-        pkgs = set(args.packages)
-        specs = [s for s in specs for p in pkgs if s.satisfies(p)]
-        display_specs(specs, args, all_headers=True)
-    else:
-        display_specs(specs, args, all_headers=True)
+        constraints = set(args.packages)
+        specs = [s for s in specs if any(s.satisfies(c) for c in constraints)]
+    display_specs(specs, args, all_headers=True)
 
 
 def getkeys(args):

lib/spack/spack/test/cmd/buildcache.py

@@ -8,11 +8,19 @@
 import pytest
 
 import spack.main
-
+import spack.binary_distribution
 
 buildcache = spack.main.SpackCommand('buildcache')
 
 
+@pytest.fixture()
+def mock_get_specs(database, monkeypatch):
+    specs = database.query_local()
+    monkeypatch.setattr(
+        spack.binary_distribution, 'get_specs', lambda x: specs
+    )
+
+
 @pytest.mark.skipif(
     platform.system().lower() != 'linux',
     reason='implementation for MacOS still missing'
@@ -20,3 +28,16 @@
 @pytest.mark.db
 def test_buildcache_preview_just_runs(database):
     buildcache('preview', 'mpileaks')
+
+
+@pytest.mark.skipif(
+    platform.system().lower() != 'linux',
+    reason='implementation for MacOS still missing'
+)
+@pytest.mark.db
+@pytest.mark.regression('13757')
+def test_buildcache_list_duplicates(mock_get_specs, capsys):
+    with capsys.disabled():
+        output = buildcache('list', 'mpileaks', '@2.3')
+
+    assert output.count('mpileaks') == 3