scripts/i18n: let 'normalized-merge' leave 3-way conflict markers in output file

3-way conflict markers in the output file can be convenient ... and they do no
harm when merge tools like kdiff3 will overwrite output anyway.

scripts/i18n

@@ -1,137 +1,140 b''
 #!/usr/bin/env python3
 
 # -*- coding: utf-8 -*-
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
 # the Free Software Foundation, either version 3 of the License, or
 # (at your option) any later version.
 #
 # This program is distributed in the hope that it will be useful,
 # but WITHOUT ANY WARRANTY; without even the implied warranty of
 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 # GNU General Public License for more details.
 #
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 import os
 import shutil
 import sys
 
 import click
 
 import i18n_utils
 
 
 """
 Tool for maintenance of .po and .pot files
 
 Normally, the i18n-related files contain for each translatable string a
 reference to all the source code locations where this string is found. This
 meta data is useful for translators to assess how strings are used, but is not
 relevant for normal development nor for running Kallithea. Such meta data, or
 derived data like kallithea.pot, will inherently be outdated, and create
 unnecessary churn and repository growth, making it harder to spot actual and
 important changes.
 """
 
 @click.group()
 @click.option('--debug/--no-debug', default=False)
 def cli(debug):
     if (debug):
         i18n_utils.do_debug = True
     pass
 
 @cli.command()
 @click.argument('po_files', nargs=-1)
 @click.option('--merge-pot-file', default=None)
 @click.option('--strip/--no-strip', default=False)
 def normalize_po_files(po_files, merge_pot_file, strip):
     """Normalize the specified .po and .pot files.
 
     By default, only actual translations and essential headers will be
     preserved, just as we want it in the main branches with minimal noise.
 
     If a .pot file is specified, the po files will instead be updated by
     running GNU msgmerge with this .pot file, thus updating source code
     references and preserving comments and outdated translations.
     """
     for po_file in po_files:
         i18n_utils._normalize_po_file(po_file, merge_pot_file=merge_pot_file, strip=strip)
 
 @cli.command()
 @click.argument('local')
 @click.argument('base')
 @click.argument('other')
 @click.argument('output')
 @click.option('--merge-pot-file', default=None)
 @click.option('--strip/--no-strip', default=False)
 def normalized_merge(local, base, other, output, merge_pot_file, strip):
     """Merge tool for use with 'hg merge/rebase/graft --tool'
 
     i18n files are partially manually editored original source of content, and
     partially automatically generated and updated. That create a lot of churn
     and often cause a lot of merge conflicts.
 
     To avoid that, this merge tool wrapper will normalize .po content before
     running the merge tool.
 
     By default, only actual translations and essential headers will be
     preserved, just as we want it in the main branches with minimal noise.
 
     If a .pot file is specified, the po files will instead be updated by
     running GNU msgmerge with this .pot file, thus updating source code
     references and preserving comments and outdated translations.
 
     Add the following to your user or repository-specific .hgrc file to use it:
         [merge-tools]
         i18n.executable = /path/to/scripts/i18n
         i18n.args = normalized-merge $local $base $other $output
 
     and then invoke merge/rebase/graft with the additional argument '--tool i18n'.
     """
     from mercurial import (
         context,
         simplemerge,
         ui as uimod,
     )
 
     print('i18n normalized-merge: merging file %s' % output)
 
     i18n_utils._normalize_po_file(local, merge_pot_file=merge_pot_file, strip=strip)
     i18n_utils._normalize_po_file(base, merge_pot_file=merge_pot_file, strip=strip)
     i18n_utils._normalize_po_file(other, merge_pot_file=merge_pot_file, strip=strip)
     i18n_utils._normalize_po_file(output, merge_pot_file=merge_pot_file, strip=strip)
 
     # simplemerge will write markers to 'local' if it fails, keep a copy without markers
     localkeep = local + '.keep'
     shutil.copyfile(local, localkeep)
 
     ret = simplemerge.simplemerge(uimod.ui.load(),
          context.arbitraryfilectx(local.encode('utf-8')),
          context.arbitraryfilectx(base.encode('utf-8')),
-         context.arbitraryfilectx(other.encode('utf-8'))
+         context.arbitraryfilectx(other.encode('utf-8')),
+         label=[b'local', b'other', b'base'],
+         mode='merge',
     )
-    shutil.copyfile(local, output)  # simplemerge wrote to local
+    shutil.copyfile(local, output)  # simplemerge wrote to local - either resolved or with conflict markers
     if ret:
+        shutil.copyfile(localkeep, local)
         basekeep = base + '.keep'
         otherkeep = other + '.keep'
         shutil.copyfile(base, basekeep)
         shutil.copyfile(other, otherkeep)
-        sys.stderr.write("Error: simple merge failed. Run a merge tool manually to resolve conflicts, then use 'hg resolve -m'.\n")
+        sys.stderr.write("Error: simple merge failed and %s is left with conflict markers. Resolve the conflics , then use 'hg resolve -m'.\n" % output)
         sys.stderr.write('Resolve with e.g.: kdiff3 %s %s %s -o %s\n' % (basekeep, localkeep, otherkeep, output))
         sys.exit(ret)
 
     os.remove(localkeep)
 
 @cli.command()
 @click.argument('file1')
 @click.argument('file2')
 @click.option('--merge-pot-file', default=None)
 @click.option('--strip/--no-strip', default=False)
 def normalized_diff(file1, file2, merge_pot_file, strip):
     """Compare two files while transparently normalizing them."""
     sys.exit(i18n_utils._normalized_diff(file1, file2, merge_pot_file=merge_pot_file, strip=strip))
 
 if __name__ == '__main__':
     cli()