Set the pointer to null upon disposing

Author: carlosmn

LibGit2Sharp/Core/Handles/Objects.cs

@@ -55,6 +55,7 @@ void Dispose(bool disposing)
                 if (owned)
                 {
                     NativeMethods.git_tree_entry_free(ptr);
+                    ptr = null;
                 }
             }
 
@@ -123,6 +124,7 @@ void Dispose(bool disposing)
                 if (owned)
                 {
                     NativeMethods.git_reference_free(ptr);
+                    ptr = null;
                 }
             }
 
@@ -191,6 +193,7 @@ void Dispose(bool disposing)
                 if (owned)
                 {
                     NativeMethods.git_repository_free(ptr);
+                    ptr = null;
                 }
             }
 

LibGit2Sharp/Core/Handles/Objects.tt

@@ -77,6 +77,7 @@ for (var i = 0; i < cNames.Length; i++)
                 if (owned)
                 {
                     NativeMethods.<#= cNames[i] #>_free(ptr);
+                    ptr = null;
                 }
             }