Git: Improve tracking of external changes to HEAD

Instead of using FileSystemWatcher, emit repositoryChanged when
refreshTopic is called.

This reverts commit 2a8c48cb15.

Fixes: QTCREATORBUG-21089
Change-Id: Iaee8a895f3bc087583cbdea11c6dc2c263694a86
Reviewed-by: André Hartmann <aha_1980@gmx.de>
Reviewed-by: Jarek Kobus <jaroslaw.kobus@qt.io>

src/plugins/git/branchmodel.cpp

@@ -11,7 +11,6 @@
 #include <vcsbase/vcsoutputwindow.h>
 
 #include <utils/environment.h>
-#include <utils/filesystemwatcher.h>
 #include <utils/qtcassert.h>
 #include <utils/qtcprocess.h>
 #include <utils/stringutils.h>
@@ -229,7 +228,6 @@ public:
     QString currentSha;
     QDateTime currentDateTime;
     QStringList obsoleteLocalBranches;
-    Utils::FileSystemWatcher fsWatcher;
     bool oldBranchesIncluded = false;
 
     struct OldEntry
@@ -257,10 +255,6 @@ BranchModel::BranchModel(GitClient *client, QObject *parent) :
     // Abuse the sha field for ref prefix
     d->rootNode->append(new BranchNode(Tr::tr("Local Branches"), "refs/heads"));
     d->rootNode->append(new BranchNode(Tr::tr("Remote Branches"), "refs/remotes"));
-    connect(&d->fsWatcher, &Utils::FileSystemWatcher::fileChanged, this, [this] {
-        QString errorMessage;
-        refresh(d->workingDirectory, &errorMessage);
-    });
 }
 
 BranchModel::~BranchModel()
@@ -422,13 +416,7 @@ bool BranchModel::refresh(const FilePath &workingDirectory, QString *errorMessag
         return false;
     }
 
-    if (d->workingDirectory != workingDirectory) {
+    d->workingDirectory = workingDirectory;
-        d->workingDirectory = workingDirectory;
-        d->fsWatcher.clear();
-        const QString gitDir = d->client->findGitDirForRepository(workingDirectory);
-        if (!gitDir.isEmpty())
-            d->fsWatcher.addFile(gitDir + "/HEAD", Utils::FileSystemWatcher::WatchModifiedDate);
-    }
     const QStringList lines = output.split('\n');
     for (const QString &l : lines)
         d->parseOutputLine(l);

src/plugins/git/gitplugin.cpp

@@ -85,29 +85,6 @@ namespace Git::Internal {
 
 using GitClientMemberFunc = void (GitClient::*)(const FilePath &) const;
 
-class GitTopicCache : public IVersionControl::TopicCache
-{
-public:
-    GitTopicCache(GitClient *client) :
-        m_client(client)
-    { }
-
-protected:
-    FilePath trackFile(const FilePath &repository) override
-    {
-        const QString gitDir = m_client->findGitDirForRepository(repository);
-        return gitDir.isEmpty() ? FilePath() : FilePath::fromString(gitDir + "/HEAD");
-    }
-
-    QString refreshTopic(const FilePath &repository) override
-    {
-        return m_client->synchronousTopic(repository);
-    }
-
-private:
-    GitClient *m_client;
-};
-
 class GitReflogEditorWidget : public GitEditorWidget
 {
 public:
@@ -437,6 +414,30 @@ public:
 
 static GitPluginPrivate *dd = nullptr;
 
+class GitTopicCache : public IVersionControl::TopicCache
+{
+public:
+    GitTopicCache(GitClient *client) :
+        m_client(client)
+    { }
+
+protected:
+    FilePath trackFile(const FilePath &repository) override
+    {
+        const QString gitDir = m_client->findGitDirForRepository(repository);
+        return gitDir.isEmpty() ? FilePath() : FilePath::fromString(gitDir + "/HEAD");
+    }
+
+    QString refreshTopic(const FilePath &repository) override
+    {
+        emit dd->repositoryChanged(repository);
+        return m_client->synchronousTopic(repository);
+    }
+
+private:
+    GitClient *m_client;
+};
+
 GitPluginPrivate::~GitPluginPrivate()
 {
     cleanCommitMessageFile();