Fix #860

httplib.h

@@ -5257,7 +5257,7 @@ inline bool ClientImpl::read_response_line(Stream &strm, const Request &req,
 
   if (!line_reader.getline()) { return false; }
 
-  const static std::regex re("(HTTP/1\\.[01]) (\\d{3}) (.*?)\r\n");
+  const static std::regex re("(HTTP/1\\.[01]) (\\d{3})(?: (.*?))?\r\n");
 
   std::cmatch m;
   if (!std::regex_match(line_reader.ptr(), m, re)) {

test/test.cc

@@ -1644,6 +1644,7 @@ TEST_F(ServerTest, GetMethod200) {
   ASSERT_TRUE(res);
   EXPECT_EQ("HTTP/1.1", res->version);
   EXPECT_EQ(200, res->status);
+  EXPECT_EQ("OK", res->reason);
   EXPECT_EQ("text/plain", res->get_header_value("Content-Type"));
   EXPECT_EQ(1, res->get_header_value_count("Content-Type"));
   EXPECT_EQ("Hello World!", res->body);