getLfsEndpointUrl(): Use our RAII helpers

src/libfetchers/git-utils.hh

@@ -127,4 +127,26 @@ struct GitRepo
 
 ref<GitRepo> getTarballCache();
 
+// A helper to ensure that the `git_*_free` functions get called.
+template<auto del>
+struct Deleter
+{
+    template <typename T>
+    void operator()(T * p) const { del(p); };
+};
+
+// A helper to ensure that we don't leak objects returned by libgit2.
+template<typename T>
+struct Setter
+{
+    T & t;
+    typename T::pointer p = nullptr;
+
+    Setter(T & t) : t(t) { }
+
+    ~Setter() { if (p) t = T(p); }
+
+    operator typename T::pointer * () { return &p; }
+};
+
 }