symlinks in pg_xlog to wal of previous timeline, after a failover

Hello all,

We have configured Streaming Replication and we see symlink in pg_xlog
pointing to another file with the previous timeline, in the same location.
This is happening after a failover. archiver errors while trying to copy
this file:
cp: cannot stat ‘pg_xlog/000000020000000000000075’: No such file or
directory
2018-01-11 23:08:24 IST LOG:  archive command failed with exit code 1
2018-01-11 23:08:24 IST DETAIL:  The failed archive command was: cp
pg_xlog/000000020000000000000075 /pgArch/edb/9.6/000000020000000000000075

-bash-4.2$ ls -ltr ../pg_xlog/000000020000000000000075
lrwxrwxrwx. 1 enterprisedb enterprisedb 24 Jan  9 16:50
../pg_xlog/000000020000000000000075 -> 000000010000000000000075
-bash-4.2$

Can somebody help understand why are these symlinks created and how to
overcome the situation?

Many Thanks