contrib/Makefile.python

filectx: add isabsent method

This will indicate whether this filectx represents a file that is *not* in a
changectx. This will be used by merge and filemerge code to know about when a
conflict is a change/delete conflict.

While this is kind of hacky, it is the least bad of all the alternatives. Other
options considered but rejected include:
- isinstance(fctx, ...) -- not very Pythonic, doesn't support duck typing
- fctx.size() is None -- the 'size()' call on workingfilectxes causes a disk stat
- fctx.filenode() == nullid -- the semantics around filenode are incredibly
  confusing. In particular, for workingfilectxes, filenode() is always None no
  matter whether the file is present on disk or in either parent. Having different
  behavior for None versus nullid in the merge code is just asking for pain.

Thanks to Pierre-Yves David for early review feedback here.

PYTHONVER=2.7.10
PYTHONNAME=python-
PREFIX=$(HOME)/bin/prefix-$(PYTHONNAME)$(PYTHONVER)
SYMLINKDIR=$(HOME)/bin

help:
	@echo
	@echo 'Make a custom installation of a Python version'
	@echo
	@echo 'Common make parameters:'
	@echo '  PYTHONVER=...    [$(PYTHONVER)]'
	@echo '  PREFIX=...       [$(PREFIX)]'
	@echo '  SYMLINKDIR=...   [$(SYMLINKDIR) creating $(PYTHONNAME)$(PYTHONVER)]'
	@echo
	@echo 'Common make targets:'
	@echo '  python    - install Python $$PYTHONVER in $$PREFIX'
	@echo '  symlink   - create a $$SYMLINKDIR/$(PYTHONNAME)$$PYTHONVER symlink'
	@echo
	@echo 'Example: create a temporary Python installation:'
	@echo '  $$ make -f Makefile.python python PYTHONVER=${PYTHONVER} PREFIX=/tmp/p27'
	@echo '  $$ /tmp/p27/bin/python -V'
	@echo '  Python 2.7'
	@echo
	@echo 'Some external libraries are required for building Python: zlib bzip2 openssl.'
	@echo 'Make sure their development packages are installed systemwide.'
# fedora: yum install zlib-devel bzip2-devel openssl-devel
# debian: apt-get install zlib1g-dev libbz2-dev libssl-dev
	@echo
	@echo 'To build a nice collection of interesting Python versions:'
	@echo '  $$ for v in 2.{6{,.1,.2,.9},7{,.8,.10}}; do'
	@echo '    make -f Makefile.python symlink PYTHONVER=$$v || break; done'
	@echo 'To run a Mercurial test on all these Python versions:'
	@echo '  $$ for py in `cd ~/bin && ls $(PYTHONNAME)2.*`; do'
	@echo '    echo $$py; $$py run-tests.py test-http.t; echo; done'
	@echo

export LANGUAGE=C
export LC_ALL=C

python: $(PREFIX)/bin/python docutils
	printf 'import sys, zlib, bz2, docutils, ssl' | $(PREFIX)/bin/python

PYTHON_SRCDIR=Python-$(PYTHONVER)
PYTHON_SRCFILE=$(PYTHON_SRCDIR).tgz

$(PREFIX)/bin/python:
	[ -f $(PYTHON_SRCFILE) ] || wget http://www.python.org/ftp/python/$(PYTHONVER)/$(PYTHON_SRCFILE) || curl -OL http://www.python.org/ftp/python/$(PYTHONVER)/$(PYTHON_SRCFILE) || [ -f $(PYTHON_SRCFILE) ]
	rm -rf $(PYTHON_SRCDIR)
	tar xf $(PYTHON_SRCFILE)
	# Ubuntu disables SSLv2 the hard way, disable it on old Pythons too
	-sed -i 's,self.*SSLv2_method(),0;//\0,g' $(PYTHON_SRCDIR)/Modules/_ssl.c
	# Find multiarch system libraries on Ubuntu and disable fortify error when setting argv
	LDFLAGS="-L/usr/lib/`dpkg-architecture -qDEB_HOST_MULTIARCH`"; \
	BASECFLAGS=-U_FORTIFY_SOURCE; \
	export LDFLAGS BASECFLAGS; \
	cd $(PYTHON_SRCDIR) && ./configure --prefix=$(PREFIX) && make all SVNVERSION=pwd && make install
	printf 'import sys, zlib, bz2, ssl' | $(PREFIX)/bin/python
	rm -rf $(PYTHON_SRCDIR)

DOCUTILSVER=0.12
DOCUTILS_SRCDIR=docutils-$(DOCUTILSVER)
DOCUTILS_SRCFILE=$(DOCUTILS_SRCDIR).tar.gz

docutils: $(PREFIX)/bin/python
	@$(PREFIX)/bin/python -c 'import docutils' || ( set -ex; \
	[ -f $(DOCUTILS_SRCFILE) ] || wget http://downloads.sourceforge.net/project/docutils/docutils/$(DOCUTILSVER)/$(DOCUTILS_SRCFILE) || [ -f $(DOCUTILS_SRCFILE) ]; \
	rm -rf $(DOCUTILS_SRCDIR); \
	tar xf $(DOCUTILS_SRCFILE); \
	cd $(DOCUTILS_SRCDIR) && $(PREFIX)/bin/python setup.py install --prefix=$(PREFIX); \
	$(PREFIX)/bin/python -c 'import docutils'; \
	rm -rf $(DOCUTILS_SRCDIR); )

symlink: python $(SYMLINKDIR)
	ln -sf $(PREFIX)/bin/python $(SYMLINKDIR)/$(PYTHONNAME)$(PYTHONVER)

.PHONY: help python docutils symlink