rlazev
diff --git a/‎LibGit2Sharp.Tests/DiffTreeToTreeFixture.cs
Lines changed: 68 additions & 1 deletion b/‎LibGit2Sharp.Tests/DiffTreeToTreeFixture.cs
Lines changed: 68 additions & 1 deletion
diff --git a/‎LibGit2Sharp/Repository.cs
Lines changed: 25 additions & 0 deletions b/‎LibGit2Sharp/Repository.cs
Lines changed: 25 additions & 0 deletions
@@ -1,4 +1,5 @@
-using System.IO;
+using System;
+using System.IO;
 using System.Linq;
 using System.Text;
 using LibGit2Sharp.Tests.TestHelpers;
@@ -388,5 +389,71 @@ public void ComparingTwoNullTreesReturnsAnEmptyTreeChanges()
                 Assert.Equal(0, changes.Count());
             }
         }
+
+        [Fact]
+        public void ComparingReliesOnProvidedConfigEntriesIfAny()
+        {
+            TemporaryCloneOfTestRepo path = BuildTemporaryCloneOfTestRepo(StandardTestRepoWorkingDirPath);
+
+            const string file = "1/branch_file.txt";
+
+            using (var repo = new Repository(path.DirectoryPath))
+            {
+                TreeEntry entry = repo.Head[file];
+                Assert.Equal(Mode.ExecutableFile, entry.Mode);
+
+                // Recreate the file in the workdir without the executable bit
+                string fullpath = Path.Combine(repo.Info.WorkingDirectory, file);
+                File.Delete(fullpath);
+                File.WriteAllBytes(fullpath, ((Blob)(entry.Target)).Content);
+
+                // Unset the local core.filemode, if any.
+                repo.Config.Unset("core.filemode", ConfigurationLevel.Local);
+            }
+
+            SelfCleaningDirectory scd = BuildSelfCleaningDirectory();
+
+            var options = BuildFakeSystemConfigFilemodeOption(scd, true);
+
+            using (var repo = new Repository(path.DirectoryPath, options))
+            {
+                TreeChanges changes = repo.Diff.Compare(new []{ file });
+
+                Assert.Equal(1, changes.Count());
+
+                var change = changes.Modified.Single();
+                Assert.Equal(Mode.ExecutableFile, change.OldMode);
+                Assert.Equal(Mode.NonExecutableFile, change.Mode);
+            }
+
+            options = BuildFakeSystemConfigFilemodeOption(scd, false);
+
+            using (var repo = new Repository(path.DirectoryPath, options))
+            {
+                TreeChanges changes = repo.Diff.Compare(new[] { file });
+
+                Assert.Equal(0, changes.Count());
+            }
+        }
+
+        private RepositoryOptions BuildFakeSystemConfigFilemodeOption(
+            SelfCleaningDirectory scd,
+            bool value)
+        {
+            Directory.CreateDirectory(scd.DirectoryPath);
+
+            var options = new RepositoryOptions
+                              {
+                                  SystemConfigurationLocation = Path.Combine(
+                                      scd.RootedDirectoryPath, "fake-system.config")
+                              };
+
+            StringBuilder sb = new StringBuilder()
+                .AppendFormat("[core]{0}", Environment.NewLine)
+                .AppendFormat("filemode = {1}{0}", Environment.NewLine, value);
+            File.WriteAllText(options.SystemConfigurationLocation, sb.ToString());
+
+            return options;
+        }
     }
 }
@@ -102,6 +102,31 @@ public Repository(string path, RepositoryOptions options = null)
             odb = new Lazy<ObjectDatabase>(() => new ObjectDatabase(this));
             diff = new Diff(this);
             notes = new NoteCollection(this);
+
+            EagerlyLoadTheConfigIfAnyPathHaveBeenPassed(options);
+        }
+
+        private void EagerlyLoadTheConfigIfAnyPathHaveBeenPassed(RepositoryOptions options)
+        {
+            if (options == null)
+            {
+                return;
+            }
+
+            if (options.GlobalConfigurationLocation == null &&
+                options.XdgConfigurationLocation == null &&
+                options.SystemConfigurationLocation == null)
+            {
+                return;
+            }
+
+            // Dirty hack to force the eager load of the configuration
+            // without Resharper pestering about useless code
+
+            if (!Config.HasConfig(ConfigurationLevel.Local))
+            {
+                throw new InvalidOperationException("Unexpected state.");
+            }
         }
 
         /// <summary>