Add test case to test ']' and '\\' characters in config subsection

tests-clar/config/read.c

@@ -164,6 +164,13 @@ void test_config_read__empty_files(void)
 	git_config_free(cfg);
 }
 
+void test_config_read__symbol_headers(void)
+{
+	git_config *cfg;
+	cl_git_pass(git_config_open_ondisk(&cfg, cl_fixture("config/config20")));
+	git_config_free(cfg);
+}
+
 void test_config_read__header_in_last_line(void)
 {
 	git_config *cfg;

tests-clar/resources/config/config20

+[valid "[subsection]"]
+    something = a
+; we don't allow anything after closing "
+[sec "[subsec]/child"]
+    parent = grand
+[sec2 "[subsec2]/child2"]
+    type = dvcs
+[sec3 "escape\"quote"]
+    vcs = git
+[sec4 "escaping\\slash"]
+    lib = git2