mergestate: make some callers not pass pointless node argument The node argument is set on the created `mergestate` instance, but these callers don't even look at that instance. Differential Revision: https://phab.mercurial-scm.org/D9031

py3: don't risk passing a None value to error.ManifestLookupError() This makes the test case added in 20dd2a259b0f (test-grep: add tests for --follow with/without --diff and/or paths, 2020-09-11) pass on Python 3. Differential Revision: https://phab.mercurial-scm.org/D9030

merge: move initial handling of mergeactions near to later one We build `mergeactions` in the beginning and use it in end. Let's build it just before where it will be used. Helps making code much easier to understand. Differential Revision: https://phab.mercurial-scm.org/D8983

upgrade: support running upgrade if repository has share-safe requirement This helps us in testing changing requirements of source repository and checking that the shared repository works. Differential Revision: https://phab.mercurial-scm.org/D8660

config: add `--shared` flag to edit config file of shared source With `format.exp-share-safe` enabled, we now read the `.hg/hgrc` of the shared source also. This patch adds `--shared` flag to `hg config` command which can be used to edit that shared source config file. It only works if the repository is shared one and is shared using the safe method. Differential Revision: https://phab.mercurial-scm.org/D8659

localrepo: load the share source .hg/hgrc also in share-safe mode (API) The second part of the Share Safe Plan is to share source repo config also. This patch adds logic to load the source repo .hg/hgrc if we are in share safe mode. On unshare, we copy and prepend source config to current repo so that config which was shared is persisted. A test is added to show that now if we enable a hook on the source repo, that also runs on the shared repositories. API change as a new optional argument sharedvfs added to localrepo.loadhgrc() Differential Revision: https://phab.mercurial-scm.org/D8656

helptext: document exp-sharesafe in internals/requirements.txt `exp-sharesafe` is a new requirement and we should document it. Differential Revision: https://phab.mercurial-scm.org/D8914

share: introduce config option to store requires in .hg/store This introduces a config option which enabled stores the requirements on a repository in store instead. When enabled, `.hg/requires` will contain the `share-safe` requirement which marks that the requirements are present in the store. This is done so that repository requirements can be shared with shares made using `hg share` command. After this patch, `hg share` checks whether the source repository has share-safe requirement, if yes, it does not copy the requirements. Test for the new functionality is added and a test case in exitsing share tests is also added. Differential Revision: https://phab.mercurial-scm.org/D8633