Also silence output of "got branch -d" in a regression test, from stsp. ok stsp

While these checks might catch usage mistakes the performance overhead of scanning the entire history of the current branch is not worth it. Measurements provided by naddy, cherrypicking 5 commits of OpenBSD's src repository in usr.bin/rsync: Before: 5m50.33s real 4m02.36s user 2m04.41s system After: 1m04.92s real 0m28.24s user 0m36.54s system Further performance improvements could be needed but this is a first step.

ok naddy

Feature requested by naddy. ok naddy, who also suggested some tweaks that will arrive shortly

Problem noticed by naddy due to failing regress tests at midnight, and then analyzed with additional help from millert. ok naddy

The git protocol spec says the client MUST NOT send a pack file if the only command used is 'delete'. Fixes 'got send -d' against Github's server which closed the session upon receiving the empty pack file we sent. This problem wasn't caught by regression tests since git-daemon does accept an empty pack file. Problem reported by jrick.

Also, make requirements for branch name arguments more flexible. Absolute reference names are now accepted. ok naddy@

Known to work against git-daemon and github Git server implementations. Tests by abieber, naddy, jrick, and myself. Man page additions reviewed by Lucas.

Once the parent commit is closed the tree_id1 pointer is no longer valid, but the pointer was still being used. Make a deep copy to fix this issue.

ok semarie

The singly-linked tail queue macros were added to OpenBSD 6.9 and are more widely available on other systems. ok stsp

ok tracey

Condense error checking to reduce a future diff moving those lines around; this pattern is already used in other parts of the tree. fine stsp ok tracey