Revert "Signal user-error on duplicate package refresh" (Bug#39187)

This reverts commit a6d87ea0.
1 job for master in 53 minutes and 16 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Test
failed #5307
test-all

00:53:16

 
Name Stage Failure
failed
test-all Test
make[2]: *** [check-doit] Error 1
Makefile:319: recipe for target 'check-doit' failed
make[1]: *** [check-expensive] Error 2
make[2]: Leaving directory '/builds/emacs/emacs/test'
Makefile:294: recipe for target 'check-expensive' failed
make[1]: Leaving directory '/builds/emacs/emacs/test'
make: *** [check-expensive] Error 2
Makefile:959: recipe for target 'check-expensive' failed
ERROR: Job failed: exit code 1