copies: inline a variable that's used only once

By inlining it, we also avoid calculating the value when "if of in
seen" is false (probably not significant).

Differential Revision: https://phab.mercurial-scm.org/D4831

mercurial/copies.py

@@ -816,11 +816,10 b' def _checkcopies(srcctx, dstctx, f, base'
     of = None
     seen = {f}
     for oc in getsrcfctx(f, msrc[f]).ancestors():
-        ocr = oc.linkrev()
         of = oc.path()
         if of in seen:
             # check limit late - grab last rename before
-            if ocr < limit:
+            if oc.linkrev() < limit:
                 break
             continue
         seen.add(of)