Merge pull request #2009 from github/fixes/1908-unicode-error

Don't change file encoding unnecessarily.

Author: jcansdale

src/GitHub.App/Services/PullRequestService.cs

@@ -769,7 +769,7 @@ public Encoding GetEncoding(ILocalRepositoryModel repository, string relativePat
                 }
             }
 
-            return Encoding.Default;
+            return null;
         }
 
         static bool HasPreamble(string file, Encoding encoding)
@@ -877,7 +877,15 @@ async Task ExtractToTempFile(
             }
 
             Directory.CreateDirectory(Path.GetDirectoryName(tempFilePath));
-            File.WriteAllText(tempFilePath, contents, encoding);
+
+            if (encoding != null)
+            {
+                File.WriteAllText(tempFilePath, contents, encoding);
+            }
+            else
+            {
+                File.WriteAllText(tempFilePath, contents);
+            }
         }
 
         IEnumerable<string> GetLocalBranchesInternal(
@@ -963,7 +971,7 @@ static string CalculateTempFileName(string relativePath, string commitSha, Encod
         {
             // The combination of relative path, commit SHA and encoding should be sufficient to uniquely identify a file.
             var relativeDir = Path.GetDirectoryName(relativePath) ?? string.Empty;
-            var key = relativeDir + '|' + encoding.WebName;
+            var key = relativeDir + '|' + (encoding?.WebName ?? "unknown");
             var relativePathHash = key.GetSha256Hash();
             var tempDir = Path.Combine(Path.GetTempPath(), "GitHubVisualStudio", "FileContents", relativePathHash);
             var tempFileName = Invariant($"{Path.GetFileNameWithoutExtension(relativePath)}@{commitSha}{Path.GetExtension(relativePath)}");

src/GitHub.Exports.Reactive/Services/IPullRequestService.cs

@@ -176,12 +176,12 @@ IObservable<IPullRequestModel> CreatePullRequest(IModelService modelService,
         IObservable<Tuple<string, int>> GetPullRequestForCurrentBranch(ILocalRepositoryModel repository);
 
         /// <summary>
-        /// Gets the encoding for the specified file.
+        /// Gets the encoding for the specified local file.
         /// </summary>
         /// <param name="repository">The repository.</param>
         /// <param name="relativePath">The relative path to the file in the repository.</param>
         /// <returns>
-        /// The file's encoding or <see cref="Encoding.Default"/> if the file doesn't exist.
+        /// The file's encoding or null if the file doesn't exist locally.
         /// </returns>
         Encoding GetEncoding(ILocalRepositoryModel repository, string relativePath);
 
@@ -192,7 +192,9 @@ IObservable<IPullRequestModel> CreatePullRequest(IModelService modelService,
         /// <param name="pullRequest">The pull request details.</param>
         /// <param name="relativePath">The path to the file, relative to the repository root.</param>
         /// <param name="commitSha">The SHA of the commit.</param>
-        /// <param name="encoding">The encoding to use.</param>
+        /// <param name="encoding">
+        /// The encoding to save the file with. If null, will use the file's original encoding.
+        /// </param>
         /// <returns>The path to the temporary file.</returns>
         Task<string> ExtractToTempFile(
             ILocalRepositoryModel repository,