test: copy test-push-http.t to testpush-http-bundle1.t

We want to keep both code paths tested. The test is a bit too extensive to
simply introduce dual testing in it, so we make a copy for each protocol
version.

tests/test-push-http-bundle1.t

@@ -1,5 +1,15 b''
 #require killdaemons
 
+This test checks behavior related to bundle1 that changed or is likely
+to change with bundle2. Feel free to factor out any part of the test
+which does not need to exist to keep bundle1 working.
+
+  $ cat << EOF >> $HGRCPATH
+  > [experimental]
+  > # This test is dedicated to interaction through old bundle
+  > bundle2-exp = False
+  > EOF
+
   $ hg init test
   $ cd test
   $ echo a > a