perf: fix the time measurement for pathcopies relative to p2
PyCharm flagged this as unused. But it seems more likely that it was intended
to reset the time for the p2 path.
Differential Revision: https://phab.mercurial-scm.org/D7742
#require symlink
https://bz.mercurial-scm.org/1438
$ hg init
$ ln -s foo link
$ hg add link
$ hg ci -mbad link
$ hg rm link
$ hg ci -mok
$ hg diff -g -r 0:1 > bad.patch
$ hg up 0
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg import --no-commit bad.patch
applying bad.patch
$ hg status
R link
? bad.patch