gptel: Handle status HTTP 100

gptel.el (gptel--url-parse-response): Handle HTTP 100 followed by
200.  Note: this fix is brittle, it will break if 100 is followed
by an error code.

gptel-curl.el (gptel-curl--stream-filter,
gptel-curl--parse-stream): Ditto.  Address karthink#194.

gptel-curl.el

@@ -201,7 +201,7 @@ PROCESS and _STATUS are process parameters."
            (http-status (plist-get info :http-status))
            (http-msg (plist-get info :status)))
       (when gptel-log-level (gptel-curl--log-response proc-buf info)) ;logging
-      (if (equal http-status "200")                                   ;Finish handling response
+      (if (member http-status '("200" "100")) ;Finish handling response
           (with-current-buffer gptel-buffer
             (if (not tracking-marker)   ;Empty response
                 (when gptel-mode (gptel--update-status " Empty response" 'success))
@@ -315,15 +315,16 @@ See `gptel--url-get-response' for details."
               display-buffer-pop-up-window)
              (reusable-frames . visible))))
         ;; Run pre-response hook
-        (when (and (equal (plist-get proc-info :http-status) "200")
+        (when (and (member (plist-get proc-info :http-status) '("200" "100"))
                    gptel-pre-response-hook)
           (with-current-buffer (marker-buffer (plist-get proc-info :position))
             (run-hooks 'gptel-pre-response-hook))))
 
       (when-let ((http-msg (plist-get proc-info :status))
                  (http-status (plist-get proc-info :http-status)))
         ;; Find data chunk(s) and run callback
-        (when-let (((equal http-status "200"))
+        ;; FIXME Handle the case where HTTP 100 is followed by HTTP (not 200) BUG #194
+        (when-let (((member http-status '("200" "100")))
                    (response (funcall (plist-get proc-info :parser) nil proc-info))
                    ((not (equal response ""))))
           (funcall (or (plist-get proc-info :callback)
@@ -385,7 +386,8 @@ PROC-INFO is a plist with contextual information."
                                      (json-read)
                                    (json-readtable-error 'json-read-error)))))
           (cond
-           ((equal http-status "200")
+           ;; FIXME Handle the case where HTTP 100 is followed by HTTP (not 200) BUG #194
+           ((member http-status '("200" "100"))
             (list (string-trim
                    (funcall parser nil response proc-info))
                   http-msg))

gptel.el

@@ -1183,7 +1183,9 @@ See `gptel-curl--get-response' for its contents.")
                                        (json-read-from-string json-str)
                                      (json-readtable-error 'json-read-error))))))
           (cond
-           ((or (= url-http-response-status 200) (string-match-p "200 OK" http-msg))
+            ;; FIXME Handle the case where HTTP 100 is followed by HTTP (not 200) BUG #194
+           ((or (memq url-http-response-status '(200 100))
+                (string-match-p "\\(?:1\\|2\\)00 OK" http-msg))
             (list (string-trim (gptel--parse-response backend response
                                              '(:buffer response-buffer)))
                    http-msg))