repro case:

1. self hosted instance
2. Have key K1 on 3 repos (R2 - R4)
3. Use Phabricator to generate a new key - K2
4. Diffusion -> R2 -> manage repository -> URIs -> existing upstream -> update credential -> pick K2 -> Update credential
5. do same for R3 & R4
6. open K1 page, says "Used by: R2, R3, R4"
7. open K2 page, "Used by" section doesn't even show

expect: after edit, K1 should lose all repos under "Used by" and they should immediately show under K2

change isn't shown:

1. immediately
2. after force-updating all the repos
3. after 10 minutes

as far as I can tell, the new key *is* used and this is just a display issue

running rev. dc2d87059b29b9dfe8838c2e0b07f4074f599112