[libsoup] Added a comment describing why it is necessary to handle the header "Transfer-Encoding: identity" al

[Claudio Saavedra <csaavedra src gnome org>]

commit 4bb95ada1045c8bcf6690b0d70c359323a27e1c5
Author: Normen Bolling <normen bolling teufel de>
Date:   Wed Aug 21 17:43:53 2019 +0200

    Added a comment describing why it is necessary to handle
    the header "Transfer-Encoding: identity" although it is
    invalid regarding RFC 7230.
    
    Issue #148

 libsoup/soup-message-headers.c | 6 ++++++
 1 file changed, 6 insertions(+)
---
diff --git a/libsoup/soup-message-headers.c b/libsoup/soup-message-headers.c
index 4e41b031..5c8c7cb9 100644
--- a/libsoup/soup-message-headers.c
+++ b/libsoup/soup-message-headers.c
@@ -664,6 +664,12 @@ static void
 transfer_encoding_setter (SoupMessageHeaders *hdrs, const char *value)
 {
        if (value) {
+               /* "identity" is a wrong value according to RFC errata 408,
+                * and RFC 7230 does not list it as valid transfer-coding.
+                * Nevertheless, the obsolete RFC 2616 stated "identity"
+                * as valid, so we can't handle it as unrecognized here
+                * for compatibility reasons.
+                */
                if (g_ascii_strcasecmp (value, "chunked") == 0)
                        hdrs->encoding = SOUP_ENCODING_CHUNKED;
                else if (g_ascii_strcasecmp (value, "identity") != 0)