16ee4f5 frontend: don't re-set Build.package value

Authored and Committed by praiskup 3 years ago
    frontend: don't re-set Build.package value
    
    When the package is already assigned to build, we don't want to
    re-assign it to a different package - even if the source RPM had a
    different name (pkg_name in /update/ route payload).  The `Package`
    object basically only holds a concrete build configuration, and so
    picking a different configuration means that the build may suddenly
    start behaving against the user's expectation (e.g. the chroot selected
    chroot list we build into may be different).
    
    Spotted in PR#1530 by @schlupov.