configitems: enable pullbundles by default

The use of pullbundles is already protected: they are only used
when a pullbundles.manifest file is created on the server.

Having an additional flag doesn't really make sense
and can confuse users (as indicated in the mercurial mailing list
on the topic "Can't get pull-bundles working").

mercurial/configitems.py

@@ -2123,7 +2123,7 b' coreconfigitem('
 coreconfigitem(
     b'server',
     b'pullbundle',
-    default=False,
+    default=True,
 )
 coreconfigitem(
     b'server',

relnotes/next

@@ -22,3 +22,7 b' Mercurial XXX.'
 == Internal API Changes ==
 
 == Miscellaneous ==
+
+ * pullbundle support no longer requires setting a server-side option,
+   providing a .hg/pullbundles.manifest according to the syntax specified in
+   'hg help -e clonebundles' is enough.

tests/test-pull-bundle.t

@@ -33,8 +33,6 b' Test pullbundle functionality'
 
   $ cd repo
   $ cat <<EOF > .hg/hgrc
-  > [server]
-  > pullbundle = True
   > [experimental]
   > evolution = True
   > [extensions]