changegroup: use a copy of hookargs when invoking the changegroup hook
addchangegroup creates a runhook function that is used to invoke the
changegroup and incoming hooks, but at the time the function is called,
the contents of hookargs associated with the transaction may have been
modified externally. For instance, bundle2 code affects it with
obsolescence markers and bookmarks info.
It also creates problems when a single transaction is used with multiple
changegroups added (as per an upcoming change), whereby the contents
of hookargs are that of after adding a latter changegroup when invoking
the hook for the first changegroup.
$ hg init a
$ cd a
$ echo 123 > a
$ hg add a
$ hg commit -m "a" -u a
$ cd ..
$ hg init b
$ cd b
$ echo 321 > b
$ hg add b
$ hg commit -m "b" -u b
$ hg pull ../a
pulling from ../a
searching for changes
abort: repository is unrelated
[255]
$ hg pull -f ../a
pulling from ../a
searching for changes
warning: repository is unrelated
requesting all changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files (+1 heads)
(run 'hg heads' to see heads, 'hg merge' to merge)
$ hg heads
changeset: 1:9a79c33a9db3
tag: tip
parent: -1:000000000000
user: a
date: Thu Jan 01 00:00:00 1970 +0000
summary: a
changeset: 0:01f8062b2de5
user: b
date: Thu Jan 01 00:00:00 1970 +0000
summary: b
$ cd ..