more details; point to apache sources where line is apparently truncated

doc/forum/error_302___40__Found__41___when_editing_page.mdwn

@@ -27,3 +27,31 @@ So I added this to Apache's config (std Debian 6.0):
 But I'm still getting the same error.
 
 Any suggestions?
+
+
+**Update 2011-08-16:** 
+[This bug report](https://bugzilla.mozilla.org/show_bug.cgi?id=513989) 
+shows the exact same symptoms; the solution they adopted is to not
+perform the redirect when the URL length exceeds the default Apache
+value of 8190.
+
+Regarding Apache limits: apparently, Apache (as of version 2.2.17)
+only applies the `LimitRequestLine` and `LimitRequestFiledsize` in
+client HTTP transactions; when dealing with the HTTP responses
+generated by CGI scripts, the code from `server/util_script.c`
+applies: (function `ap_scan_script_header_err_core`, lines 403--433)
+
+        char x[MAX_STRING_LEN];
+        char *w, *l;
+        [...]
+        if (buffer) {
+            *buffer = '\0';
+        }
+        w = buffer ? buffer : x;
+        [...]
+        while (1) {
+            int rv = (*getsfunc) (w, MAX_STRING_LEN - 1, getsfunc_data);
+
+where `MAX_STRING_LEN` is defined in `httpd.h` to be equal to
+`HUGE_STRING_LEN`, that is, 8192.
+