tests/test-convert-authormap.t

import-checker: establish modern import convention

We introduce a new convention for declaring imports and enforce it via
the import checker script.

The new convention is only active when absolute imports are used, which is
currently nowhere. Keying off "from __future__ import absolute_import" to
engage the new import convention seems like the easiest solution. It is
also beneficial for Mercurial to use this mode because it means less work
and ambiguity for the importer and potentially better performance due to
fewer stat() system calls because the importer won't look for modules in
relative paths unless explicitly asked.

Once all files are converted to use absolute import, we can refactor
this code to again only have a single import convention and we can
require use of absolute import in the style checker.

The rules for the new convention are documented in the docstring of the
added function. Tests have been added to test-module-imports.t. Some
tests are sensitive to newlines and source column position, which makes
docstring testing difficult and/or impossible.

  $ cat >> $HGRCPATH <<EOF
  > [extensions]
  > convert=
  > EOF

Prepare orig repo

  $ hg init orig
  $ cd orig
  $ echo foo > foo
  $ HGUSER='user name' hg ci -qAm 'foo'
  $ cd ..

Explicit --authors

  $ cat > authormap.txt <<EOF
  > user name = Long User Name
  > 
  > # comment
  > this line is ignored
  > EOF
  $ hg convert --authors authormap.txt orig new
  initializing destination new repository
  ignoring bad line in author map file authormap.txt: this line is ignored
  scanning source...
  sorting...
  converting...
  0 foo
  writing author map file $TESTTMP/new/.hg/authormap (glob)
  $ cat new/.hg/authormap
  user name=Long User Name
  $ hg -Rnew log
  changeset:   0:d89716e88087
  tag:         tip
  user:        Long User Name
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     foo
  
  $ rm -rf new

Implicit .hg/authormap

  $ hg init new
  $ mv authormap.txt new/.hg/authormap
  $ hg convert orig new
  ignoring bad line in author map file $TESTTMP/new/.hg/authormap: this line is ignored (glob)
  scanning source...
  sorting...
  converting...
  0 foo
  $ hg -Rnew log
  changeset:   0:d89716e88087
  tag:         tip
  user:        Long User Name
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     foo