Git: Factor out pattern for invalid branch names

Re-use it in the follow-up commit for remote names also.

Change-Id: Ib88792a1abdc2fa8ac23c99aa7d4861728e36eec
Reviewed-by: Orgad Shaneh <orgads@gmail.com>
Reviewed-by: Tobias Hunger <tobias.hunger@qt.io>

src/plugins/git/branchadddialog.cpp

@@ -25,6 +25,7 @@
 
 #include "branchadddialog.h"
 #include "ui_branchadddialog.h"
+#include "gitplugin.h"
 
 #include <utils/hostosinfo.h>
 
@@ -47,20 +48,7 @@ class BranchNameValidator : public QValidator
 public:
     BranchNameValidator(const QStringList &localBranches, QObject *parent = 0) :
         QValidator(parent),
-        m_invalidChars(
-            "\\s"     // no whitespace
-            "|~"      // no "~"
-            "|\\^"    // no "^"
-            "|\\["    // no "["
-            "|\\.\\." // no ".."
-            "|/\\."   // no slashdot
-            "|:"      // no ":"
-            "|@\\{"   // no "@{" sequence
-            "|\\\\"   // no backslash
-            "|//"     // no double slash
-            "|^[/-]"  // no leading slash or dash
-            "|\""     // no quotes
-        ),
+        m_invalidChars(GitPlugin::invalidBranchAndRemoteNamePattern()),
         m_localBranches(localBranches)
     {
     }