pack: free the new pack struct if we fail to insert

If we fail to insert the packfile in the map, make sure to free it.

This makes the free function only attempt to remove its mwindows from
the global list if we have opened the packfile to avoid accessing the
list unlocked.

src/mwindow.c

@@ -67,6 +67,7 @@ int git_mwindow_get_pack(struct git_pack_file **out, const char *path)
 
 	if (git_mwindow_files_init() < 0) {
 		git_mutex_unlock(&git__mwindow_mutex);
+		git__free(packname);
 		return -1;
 	}
 
@@ -93,8 +94,10 @@ int git_mwindow_get_pack(struct git_pack_file **out, const char *path)
 	git_strmap_insert(git__pack_cache, pack->pack_name, pack, error);
 	git_mutex_unlock(&git__mwindow_mutex);
 
-	if (error < 0)
+	if (error < 0) {
+		git_packfile_free(pack);
 		return -1;
+	}
 
 	*out = pack;
 	return 0;

src/pack.c

@@ -968,10 +968,10 @@ void git_packfile_free(struct git_pack_file *p)
 
 	cache_free(&p->bases);
 
-	git_mwindow_free_all_locked(&p->mwf);
-
-	if (p->mwf.fd >= 0)
+	if (p->mwf.fd >= 0) {
+		git_mwindow_free_all_locked(&p->mwf);
 		p_close(p->mwf.fd);
+	}
 
 	pack_index_free(p);