[MERGE] Fix bugs #245964, #265070, #270863 and #303959 by handling redirections better

[Vincent Ladeuil]

>>>>> "robert" == Robert Collins <robertc at robertcollins.net> writes:

    robert> Robert Collins has voted tweak.
    robert> Status is now: Conditionally approved
    robert> Comment:
    robert> +        if scheme in ('http', 'https'):
    robert> +            # Same protocol (i.e. http[s])

    robert> This smells a little - other protocols could be similar too no?

Only http can generate redirections ?

    robert> Ok to merge as is, but perhaps a
    robert> bug/comment/something that this hardcoded rather than
    robert> generic.

It's already in bzrlib.transport.http so it *is* specific to
http/https.

Anyway, I've added:

-            # Same protocol (i.e. http[s])
+            # Same protocol family (i.e. http[s]), we will preserve the same
+            # http client implementation when a redirection occurs from one to
+            # the other (otherwise users may be surprised that bzr switches
+            # from one implementation to the other, and devs may suffer
+            # debugging it).


Does that address your concern ?

If not, just tell me and I'll do a followup patch, redirection
bugs have been are hard to diagnose so adding better comments
can't hurt.

     Vincent