Requested by James Cook

Problem reported by James Cook with reproduction scripts Regression test case by jamsek, as a simplified version of James' scripts fix tested + ok jamsek

Otherwise we leave unversioned files behind in the work tree which may interfere with new attempts to rebase or merge the changes again. Problem found by + ok naddy@

problem found by robert@ ok jamsek, op

The commands 'got rebase -a' and 'got histedit -a' were checking out files from the wrong commit. Make them check files out from the commit we are switching the work tree to, as intended. Avoids spurious merge conflicts when the work tree is later used for another rebase operation. It also makes 'got update' right after 'rebase -a' a no-op, as it should be. Problem found by naddy@ while rebasing jca's llvm15 branch ok op, jamsek earlier version

This avoids having to run 'got update' after operations which run checkout_files() and where a file happens to have the same blob ID but its base commit differs from the commit we are updating to. Found while investigating a bug report by naddy@ ok op, jamsek (earlier version)

problem found by naddy@

problem found by naddy@ ok op@

It will soon grow functions to deal with sha256 too. stsp@ agrees.

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>

To skip chunks without newly added lines. ok stsp@

ok jamsek

Rather than skip lines, use the new diff APIs to directly seek to each chunk with newly added lines for more efficient conflict marker detection. ok stsp@