rebase: allow rebase even if some revisions need no rebase (BC) (issue5422) This allows you to do e.g. "hg rebase -d @ -r 'draft()'" even if some drafts are already based off of @. You'd still need to exclude obsolete and troubled revisions, though. We will deal with those cases later. Implemented by treating state[rev]==rev as "no need to rebase". I considered adding another fake revision number like revdone=-6. That would make the code clearer in a few places, but would add extra code in other places. I moved the existing test out of test-rebase-base.t and into a new file and added more tests there, since not all are using --base.

chgserver: more explicit about sensitive environ variables Environment variables like HGUSER, HGEDITOR, HGEDITFROM should not trigger a new chgserver. This patch uses a whitelist for environ variables starting with "HG" to reduce the number of servers. I have went through `grep -o "[\"']HG[A-Z_0-9]*['\"]" -hR . | sort -u` so the list should be up-to-date.

scmutil: make simplekeyvaluefile able to have a non-key-value first line To ease migration from files with version numbers in their first lines, we want simplekeyvaluefile to support a non-key-value first line. In this way, old versions of Mercurial will read such files, discover a newer version than the one they know how to handle and fail gracefully, rather than with exception. Shelve's shelvestate file is an example.

scmutil: add simplekeyvaluefile reading test Before this patch, mockvfs did not emulate readlines correctly and there was no test for simplekeyvaluefile reading.