From d42c8fbd14a544f1571b47354fde28264b53d890 Mon Sep 17 00:00:00 2001
From: "Mr. Outis" <mroutis@protonmail.com>
Date: Wed, 24 Apr 2019 16:01:57 -0700
Subject: [PATCH] repro: persisting outputs invalidates build cache

Fix #1852
---
 dvc/stage.py           |  4 ++++
 tests/func/test_run.py | 31 +++++++++++++++++++++++++++++++
 2 files changed, 35 insertions(+)

diff --git a/dvc/stage.py b/dvc/stage.py
index 62ea6278f5..3e0e81e005 100644
--- a/dvc/stage.py
+++ b/dvc/stage.py
@@ -502,6 +502,10 @@ def create(
         else:
             stage.unprotect_outs()
 
+        if os.path.exists(path) and any(out.persist for out in stage.outs):
+            logger.warning("Build cache is ignored when persisting outputs.")
+            ignore_build_cache = True
+
         if validate_state:
             if os.path.exists(path):
                 if not ignore_build_cache and stage.is_cached:
diff --git a/tests/func/test_run.py b/tests/func/test_run.py
index 9015e4eab1..f789f1436d 100644
--- a/tests/func/test_run.py
+++ b/tests/func/test_run.py
@@ -1,6 +1,7 @@
 import os
 import uuid
 
+import logging
 import mock
 import shutil
 import filecmp
@@ -948,3 +949,33 @@ def test(self):
 
                     mock_run.assert_called_once()
                     mock_checkout.assert_not_called()
+
+
+class TestPersistentOutput(TestDvc):
+    def test_ignore_build_cache(self):
+        warning = "Build cache is ignored when persisting outputs."
+
+        with open("immutable", "w") as fobj:
+            fobj.write("1")
+
+        cmd = [
+            "run",
+            "--overwrite-dvcfile",
+            "--deps",
+            "immutable",
+            "--outs-persist",
+            "greetings",
+            "echo hello>>greetings",
+        ]
+
+        with self._caplog.at_level(logging.WARNING, logger="dvc"):
+            assert main(cmd) == 0
+            assert warning not in self._caplog.text
+
+            assert main(cmd) == 0
+            assert warning in self._caplog.text
+
+        # Even if the "immutable" dependency didn't change
+        # it should run the command again, as it is "ignoring build cache"
+        with open("greetings", "r") as fobj:
+            assert "hello\nhello\n" == fobj.read()