--- a/mercurial/remotenames.py	Thu Oct 05 01:31:53 2017 +0530
+++ b/mercurial/remotenames.py	Thu Nov 09 12:10:03 2017 +0530
@@ -64,6 +64,12 @@
     # version '0' represents the very initial version of the storage format
     f.write('0\n\n')
 
+    olddata = set(readremotenamefile(repo, nametype))
+    # re-save the data from a different remote than this one.
+    for node, oldpath, rname in sorted(olddata):
+        if oldpath != remotepath:
+            f.write('%s\0%s\0%s\n' % (node, oldpath, rname))
+
     for name, node in sorted(names.iteritems()):
         if nametype == "branches":
             for n in node:

--- a/tests/test-remotenames.t	Thu Oct 05 01:31:53 2017 +0530
+++ b/tests/test-remotenames.t	Thu Nov 09 12:10:03 2017 +0530
@@ -102,10 +102,15 @@
   $ cat .hg/remotenames/bookmarks
   0
   
+  62615734edd52f06b6fb9c2beb429e4fe30d57b8\x00file:$TESTTMP/server\x00foo (esc)
+  87d6d66763085b629e6d7ed56778c79827273022\x00file:$TESTTMP/server\x00bar (esc)
   87d6d66763085b629e6d7ed56778c79827273022\x00file:$TESTTMP/server2\x00bar (esc)
   62615734edd52f06b6fb9c2beb429e4fe30d57b8\x00file:$TESTTMP/server2\x00foo (esc)
+
   $ cat .hg/remotenames/branches
   0
   
+  3e1487808078543b0af6d10dadf5d46943578db0\x00file:$TESTTMP/server\x00wat (esc)
+  ec2426147f0e39dbc9cef599b066be6035ce691d\x00file:$TESTTMP/server\x00default (esc)
   ec2426147f0e39dbc9cef599b066be6035ce691d\x00file:$TESTTMP/server2\x00default (esc)
   3e1487808078543b0af6d10dadf5d46943578db0\x00file:$TESTTMP/server2\x00wat (esc)