Issue #226: Built-in Mercurial Hooks (Read-Only) are not readonly (conservancy/kallithea)

[fragpit]

New issue 226: Built-in Mercurial Hooks (Read-Only) are not readonly
https://bitbucket.org/conservancy/kallithea/issues/226/built-in-mercurial-hooks-read-only-are-not

fragpit:

Hello, 

faced with problem: 

open
http://server/_admin/settings/hooks

add hook with existing name, for example - preoutgoing.pre_pull. 
New value would rewrite an old one. 

If I add nonexistent hook name, It would be added as Custom hook. 

Seems like UI problem, that built-in values are not readonly.