removing directories from repository

[Talden]

>> Is it possible to permanently remove a directory from the history of a
>> branch? ie.I have some tree external/mydir, I want to do a command
>> such that it is removed as though it was never in the repository.
>>
>> If it is not possible, how hard would it be to implement?
>>
>> The most obvious application of this is someone adds a big file by
>> mistake to the repo (or a library), and then you are stuck with all
>> those files for eternity.
>
> This seems to be a very frequently asked question.  Perhaps we should
> document the answer somewhere in the user guide or elsewhere.

True, though unfortunately the answer is mostly "no we don't have a
way of doing that - here are some not quite equivalent hacks".

We need to
1) Clearly explain the consequences of changing past commits - anyone
with a mirror or a branch based on this branch needs to start-over as
history has changed.

2) Provide a means of scrubbing through a repo stripping a set of
paths/patterns and rewriting the commits (same author, time, ... but a
different id).  To make the task easier This could just write a new
repo without the stripped content rather than rewrite the existing
repo.  There are other uses we might consider as well of course. EG
Affecting only a particular set of branches (which means creating
non-related but very similar commits for the affected branches whilst
not changing the commits for branches we want to keep unchanged - more
space used, so this choice wouldn't be about storage space).


Currently, as I understand it, we have only somewhat incomplete
solutions to the problem.

--
Talden