pmbootstrap tries to install conflicting icu-data-en and icu-data-full

From https://builds.sr.ht/~postmarketos/job/766757#task-img-380:

ERROR: unable to select packages:                                                                                                                              
  icu-data-en-71.1-r2:                                                                                                                                         
    conflicts: icu-data-full-71.1-r2[icu-data=71.1-r2]                                                                                                         
    satisfies: .pmbootstrap-20220527.073240[icu-data-en]                       
               icu-libs-71.1-r2[icu-data=71.1-r2]                              
  icu-data-full-71.1-r2:               
    conflicts: icu-data-en-71.1-r2[icu-data=71.1-r2]                           
    satisfies: qt5-qtbase-5.15.4_git20220511-r1[icu-data-full]                 
               .pmbootstrap-20220527.073240[icu-data-full]                     
               icu-libs-71.1-r2[icu-data=71.1-r2]                              
  .pmbootstrap-20220527.073240:        
    masked in: cache                   
    satisfies: world[.pmbootstrap=20220527.073240]   

I can reproduce this outside of bpo.

What happens:

• firefox-esr depends on icu-data, which is provided by icu-data-en and icu-data-full
• icu-data-en and icu-data-full are conflicting
• icu-data-en has a higher priority, so pmbootstrap chooses it
• qt5-qtbase depends on icu-data-full
• so pmbootstrap tries to install both

firefox-esr
-> so:libicui18n.so.71
-> icu-libs
-> icu-data
-> icu-data-en | icu-data-full