sharding: Don't inject shard ranges when user says quit

When an operator does a `find_and_replace` on a DB that already has
shard ranges, they get a prompt like:

   This will delete existing 58 shard ranges.
   Do you want to show the existing ranges [s], delete the existing
   ranges [yes] or quit without deleting [q]?

Previously, if they selected `q`, we would skip the delete but still do
the merge (!) and immediately warn about how there are now invalid shard
ranges. Now, quit without merging.

Cherry-Picked-From: I7d869b137a6fbade59bb8ba16e4f3e9663e18822
Change-Id: I7ee69f0ca1aeef1004e61c45eeeb98dd35fe212e

2 files changed, 21 insertions, 2 deletions

diff --git a/swift/cli/manage_shard_ranges.py b/swift/cli/manage_shard_ranges.py
index 667304d57..e482e7f68 100644
--- a/swift/cli/manage_shard_ranges.py
+++ b/swift/cli/manage_shard_ranges.py
@@ -343,7 +343,9 @@ def _replace_shard_ranges(broker, args, shard_data, timeout=0):
 
     # Crank up the timeout in an effort to *make sure* this succeeds
     with broker.updated_timeout(max(timeout, args.replace_timeout)):
-        delete_shard_ranges(broker, args)
+        delete_status = delete_shard_ranges(broker, args)
+        if delete_status != 0:
+            return delete_status
         broker.merge_shard_ranges(shard_ranges)
 
     print('Injected %d shard ranges.' % len(shard_ranges))
diff --git a/test/unit/cli/test_manage_shard_ranges.py b/test/unit/cli/test_manage_shard_ranges.py
index 11f6420e4..65bcd0dd6 100644
--- a/test/unit/cli/test_manage_shard_ranges.py
+++ b/test/unit/cli/test_manage_shard_ranges.py
@@ -358,6 +358,23 @@ class TestManageShardRanges(unittest.TestCase):
         self.assertEqual(['Loaded db broker for a/c.'],
                          err.getvalue().splitlines())
         self._assert_enabled(broker, now)
+        found_shard_ranges = broker.get_shard_ranges()
         self.assertEqual(
             [(data['lower'], data['upper']) for data in self.shard_data],
-            [(sr.lower_str, sr.upper_str) for sr in broker.get_shard_ranges()])
+            [(sr.lower_str, sr.upper_str) for sr in found_shard_ranges])
+
+        # Do another find & replace but quit when prompted about existing
+        # shard ranges
+        out = StringIO()
+        err = StringIO()
+        to_patch = 'swift.cli.manage_shard_ranges.input'
+        with mock.patch('sys.stdout', out), mock.patch('sys.stderr', err), \
+                mock_timestamp_now() as now, \
+                mock.patch(to_patch, return_value='q'):
+            main([broker.db_file, 'find_and_replace', '10'])
+        # Shard ranges haven't changed at all
+        self.assertEqual(found_shard_ranges, broker.get_shard_ranges())
+        expected = ['This will delete existing 10 shard ranges.']
+        self.assertEqual(expected, out.getvalue().splitlines())
+        self.assertEqual(['Loaded db broker for a/c.'],
+                         err.getvalue().splitlines())