rebase: fix bug that caused transitive copy records to disappear (
issue4192)
The defect was that copies were always duplicated against the target
revision, rather than the first parent of the revision being
rebased. This produced nominally correct results if changes were
rebased one at a time (or with --collapse), but was wrong if we
rebased a sequence of changesets which contained a sequence of copies.
Minimal hgk check
$ echo "[extensions]" >> $HGRCPATH
$ echo "hgk=" >> $HGRCPATH
$ hg init repo
$ cd repo
$ echo a > a
$ hg ci -Am adda
adding a
$ hg debug-cat-file commit 0
tree a0c8bcbbb45c
parent 000000000000
author test 0 0
revision 0
branch default
phase draft
adda
$ cd ..