gotadmin dump is used to export (part of) the history of the repository; at the moment it only generates git bundles (which are pack files with a header) but support to generate a fast-import stream is planned. ok/tweaks stsp and jamsek

This adds the functions got_repo_cleanup_prepare() and _complete() to lock/unlock the repository to prevent multiple `gotadmin cleanup' or `git gc' operations to run in parallel. improvements and ok stsp@

improvements and ok stsp@

In preparation for wide sha256 support; stsp@ agrees. Change done mechanically with find . -iname \*.[cy] -exec sam {} + X ,x/<sha1\.h>/i/\n#include <sha2.h>

Intended mostly for the regress suite, so we'll be able to test also the ref-delta code paths. ok stsp@

In the case of tog move setlocale(3) before pledge(2), as suggested by stsp. ok stsp@

got_repo_get_gitconfig_extensions is only used in gotadmin to check if the preciousObjects extension is active; let's replace it with a function that just checks whether a certain extension is active. It simplifies future changes to the extensions handling. ok stsp@

Accept flag parameter to optionally specify which pointers to free. This saves callers looping through the list to free pointers. ok + fix stsp@

The -h and -V/--version flags must be given before the command; with those flags the command is actually optional, but don't over-complicate the usage string with these nitpicks. ok/improvements stsp@

Similar to `git init -b`. Includes a change to `got import` behaviour such that "main" is no longer hardcoded by default; instead, we import to the branch resolved via the repository's HEAD reference unless `got import -b` is used, and only if HEAD cannot be resolved to a branch do we fallback to "main". includes fix plus ok from stsp@

patch by Josiah Frentsos

This functionality is better suited for gotadmin because it is technically a server-side repository operation when we consider the 'got' tool as the client-side tool. I have plans to move 'got import' into gotadmin as well. ok op@