record: use absolute path instead of os.chdir

Record was changing the current directory to `repo.root` in order to be able to
feed `command.commit` file name relative to this `repo.root`. This is a bit
overkill and prevent an incoming fix to rebase. This would also break
multi-threaded usage.

Instead we just feed `command.commit` with absolute path name. works as well as
before but without chdir.

hgext/record.py

@@ -601,12 +601,8 b' def dorecord(ui, repo, commitfunc, cmdsu'
             # it is important to first chdir to repo root -- we'll call
             # a highlevel command with list of pathnames relative to
             # repo root
-            cwd = os.getcwd()
-            os.chdir(repo.root)
-            try:
+            newfiles = [repo.wjoin(nf) for nf in newfiles]
                 commitfunc(ui, repo, *newfiles, **opts)
-            finally:
-                os.chdir(cwd)
 
             return 0
         finally: