http: return error for a second Location: header

Unless it is identical to the previous one.

Follow-up to dbcaa00657

Adjusted test 580, added test 772 and 773

Fixes #19130
Reported-by: Jakub Stasiak
Closes #19134

tests/data/test772

@@ -0,0 +1,52 @@
+<testcase>
+<info>
+<keywords>
+HTTP
+HTTP GET
+Location
+</keywords>
+</info>
+
+#
+# Server-side
+<reply>
+<data crlf="yes" nocheck="yes">
+HTTP/1.1 200 OK
+Date: Tue, 09 Nov 2010 14:49:00 GMT
+Content-Length: 0
+Connection: close
+Location: this
+Location: that
+
+</data>
+</reply>
+
+#
+# Client-side
+<client>
+<server>
+http
+</server>
+<name>
+HTTP with two Location: headers triggers error
+</name>
+<command>
+http://%HOSTIP:%HTTPPORT/%TESTNUMBER
+</command>
+</client>
+
+#
+# Verify data after the test has been "shot"
+<verify>
+<protocol crlf="yes">
+GET /%TESTNUMBER HTTP/1.1
+Host: %HOSTIP:%HTTPPORT
+User-Agent: curl/%VERSION
+Accept: */*
+
+</protocol>
+<errorcode>
+8
+</errorcode>
+</verify>
+</testcase>