The syntax to compare strings is

      STRING1 = STRING2
                     True if the strings are equal.
      STRING1 != STRING2
                     True if the strings are not equal.

STRING1=STRING2 is not a valid syntax for strings comparisons.

This is same fix as 6cf1769d (ERP5: fix handling of repozo restoration
failure, 2024-10-24) and also a fix to a wrong error message, because
this is not restoration script, it's backup script.