Index: subversion/libsvn_client/merge.c
===================================================================
--- subversion/libsvn_client/merge.c	(revision 28740)
+++ subversion/libsvn_client/merge.c	(working copy)
@@ -1219,6 +1219,7 @@
   const char *min_url = (revision1 < revision2) ? url1 : url2;
   const char *max_url = (revision1 < revision2) ? url2 : url1;
   const char *min_rel_path, *max_rel_path;
+  svn_error_t *err;
 
   SVN_ERR(svn_client__path_relative_to_root(&min_rel_path, min_url,
                                             source_root_url, FALSE, ra_session,
@@ -1233,25 +1234,38 @@
                                           min_rel_path, min_rev,
                                           svn_mergeinfo_inherited, TRUE,
                                           pool));
-  SVN_ERR(svn_client__get_repos_mergeinfo(ra_session, &end_mergeinfo,
-                                          max_rel_path, max_rev,
-                                          svn_mergeinfo_inherited, TRUE,
-                                          pool));
-
-  SVN_ERR(svn_mergeinfo_diff(&deleted_mergeinfo, &added_mergeinfo,
-                             start_mergeinfo, end_mergeinfo,
-                             FALSE, pool));
-
-  if (added_mergeinfo)
+  err = svn_client__get_repos_mergeinfo(ra_session, &end_mergeinfo,
+                                        max_rel_path, max_rev,
+                                        svn_mergeinfo_inherited, TRUE,
+                                        pool);
+  /* When operating on subtrees with intersecting mergeinfo, URL1@REVISION1
+     might have been deleted and URL2@REVISION2 won't exist.  Don't return an
+     error in this case, just proceed without bothering to look for
+     ADDED_MERGEINFO. */
+  if (err)
     {
-      const char *mergeinfo_path;
-      SVN_ERR(svn_client__path_relative_to_root(&mergeinfo_path, target_url,
-                                                source_root_url, TRUE,
-                                                ra_session, NULL, pool));
-      src_rangelist_for_tgt = apr_hash_get(added_mergeinfo, mergeinfo_path,
-                                           APR_HASH_KEY_STRING);
+      if (err->apr_err == SVN_ERR_FS_NOT_FOUND
+          || err->apr_err == SVN_ERR_RA_DAV_REQUEST_FAILED)
+        svn_error_clear(err);
+      else
+        return err;
     }
+  else
+    {
+      SVN_ERR(svn_mergeinfo_diff(&deleted_mergeinfo, &added_mergeinfo,
+                                 start_mergeinfo, end_mergeinfo,
+                                 FALSE, pool));
 
+      if (added_mergeinfo)
+        {
+          const char *mergeinfo_path;
+          SVN_ERR(svn_client__path_relative_to_root(&mergeinfo_path, target_url,
+                                                    source_root_url, TRUE,
+                                                    ra_session, NULL, pool));
+          src_rangelist_for_tgt = apr_hash_get(added_mergeinfo, mergeinfo_path,
+                                               APR_HASH_KEY_STRING);
+        }
+    }
   /* Create a single-item list of ranges with our one requested range
      in it, and then remove overlapping revision ranges from that range. */
   *requested_rangelist = apr_array_make(pool, 1, sizeof(range));
@@ -5215,6 +5229,7 @@
                                "it has descendents with different revisions "
                                "merged", source_repos_rel_path);
     }
+  return SVN_NO_ERROR;
 }