Convert (most) scripts to Python 3.

Missing: the development web server. I don't think that sees much use,
we can convert it to http.server when/if someone ever needs it on a box
without python2.

backend/example-backend.py

-#!/usr/bin/python
+#!/usr/bin/env python
 #
 # This is a simple web server (listening to port 5911) that takes the
 # X-UA-Device header into consideration when producing content.
 #
 # Author: Lasse Karstensen <lkarsten@varnish-software.com>, February 2012.
+#
+from __future__ import print_function
 from BaseHTTPServer import HTTPServer, BaseHTTPRequestHandler
 from socket import AF_INET6
 from pprint import pformat
@@ -59,13 +61,10 @@ class requesthandler(BaseHTTPRequestHandler):
         self.wfile.write("<p>This page was generated %s.</p>" % (datetime.datetime.now().isoformat()))
         self.wfile.write(TAIL_CONTENT)
 
-def main():
+if __name__ == "__main__":
     server_address = ('', 5911)
     HTTPServer.allow_reuse_address = True
     HTTPServer.address_family = AF_INET6
     httpd = HTTPServer(server_address, requesthandler)
-    print "Listening on %s:%s." % server_address
+    print("Listening on %s:%s." % server_address)
     httpd.serve_forever()
-
-if __name__ == "__main__":
-    main()

tests/vtc-from-controlset.py

-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 Parse the list of manually classified User-Agent strings and
 prepare a varnishtest test case that verifies the correct classification.
@@ -25,9 +25,9 @@ TAILER="""}
 client c1 -run
 """
 
-def main():
+if __name__ == "__main__":
     inputfile = argv[1]
-    print HEADER
+    print(HEADER)
     for line in open(inputfile):
         line = line.strip()
         if line.startswith("#") or len(line) == 0:
@@ -36,10 +36,8 @@ def main():
 
         classid, uastring = line.split("\t", 1)
 
-        print "\ttxreq -hdr \"User-Agent: %s\"" % uastring
-        print "\trxresp"
-        print "\texpect resp.http.X-UA-Device == \"%s\"\n" % classid
-    print TAILER
+        print("\ttxreq -hdr \"User-Agent: %s\"" % uastring)
+        print("\trxresp")
+        print("\texpect resp.http.X-UA-Device == \"%s\"\n" % classid)
+    print(TAILER)
 
-if __name__ == "__main__":
-    main()

tests/vtc-from-snippets.py

-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 Pick out the examples from the installation documentation and
 build a VTC test case around it.
@@ -60,9 +60,9 @@ def parse(inputfile):
                 assert section is not None
                 assert line.startswith(".. endsnippet-%s" % section)
             except AssertionError:
-                print section, line
-                print buf
-                print req
+                print(section, line)
+                print(buf)
+                print(req)
                 raise
 
             yield section, "".join(buf), "   ".join(req)
@@ -82,6 +82,6 @@ if __name__ == "__main__":
     rstfile = argv[1]
     for name, testsnippet, req in parse(rstfile):
         with open("snippet-%s.vtc" % name, "w+") as fp:
-            print >>fp, header(name)
-            print >>fp, testsnippet
-            print >>fp, tailer(req)
+            print(header(name), file=fp)
+            print(testsnippet, file=fp)
+            print(tailer(req), file=fp)