copies: don't detect copies as "divergent renames"

(For the purposes of this patch copy is defined as a rename where the
source continues to exist.)

mercurial/copies.py

@@ -195,8 +195,8 b' def copies(repo, c1, c2, ca, checkdirs=F'
 
     diverge2 = set()
     for of, fl in diverge.items():
-        if len(fl) == 1:
-            del diverge[of] # not actually divergent
+        if len(fl) == 1 or of in c2:
+            del diverge[of] # not actually divergent, or not a rename
         else:
             diverge2.update(fl) # reverse map for below
 

tests/test-rename-merge1.t

@@ -75,3 +75,27 b''
   $ hg debugrename b
   b renamed from a:dd03b83622e78778b403775d0d074b9ac7387a66
 
+This used to trigger a "divergent renames" warning, despite no renames
+
+  $ hg cp b b3
+  $ hg cp b b4
+  $ hg ci -A -m 'copy b twice'
+  $ hg up eb92d88a9712
+  0 files updated, 0 files merged, 2 files removed, 0 files unresolved
+  $ hg up
+  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  $ hg rm b3 b4
+  $ hg ci -m 'clean up a bit of our mess'
+
+We'd rather not warn on divergent renames done in the same changeset (issue2113)
+
+  $ hg cp b b3
+  $ hg mv b b4
+  $ hg ci -A -m 'divergent renames in same changeset'
+  $ hg up c761c6948de0
+  1 files updated, 0 files merged, 2 files removed, 0 files unresolved
+  $ hg up
+  warning: detected divergent renames of b to:
+   b3
+   b4
+  2 files updated, 0 files merged, 1 files removed, 0 files unresolved