There are other files that do this, too, such as doc/en/admin-guide/introduction.txt; take a look at the results of this highly scientific grep:

bzr ls -RV0 | xargs -0 grep -nH -e 'python.*2\.[0-5]' -i
INSTALL:7:bzr requires Python2.4 and cElementTree:
bzrlib/__init__.py:52:# Python version 2.0 is (2, 0, 0, 'final', 0)."  Additionally we use a
bzrlib/_btree_serializer_pyx.pyx:20:#python2.4 support
bzrlib/_chk_map_pyx.pyx:18:#python2.4 support
bzrlib/_chunks_to_lines_pyx.pyx:20:#python2.4 support
bzrlib/_dirstate_helpers_pyx.pyx:43:#python2.4 support, and other platform-dependent includes
bzrlib/_dirstate_helpers_pyx.pyx:1616:                        # on win32, python2.4 has e.errno == ERROR_DIRECTORY, but
bzrlib/_dirstate_helpers_pyx.pyx:1617:                        # python 2.5 has e.errno == EINVAL,
bzrlib/_export_c_api.h:48:    /* (char *) is because python2.4 declares this api as 'char *' rather than
bzrlib/_groupcompress_pyx.pyx:19:#python2.4 support
bzrlib/_import_c_api.h:50:    /* (char *) because Python2.4 defines this as (char *) rather than
bzrlib/_patiencediff_py.py:233:        # jam 20060525 This is the python 2.4.1 difflib get_matching_blocks
bzrlib/_readdir_pyx.pyx:23:#python2.4 support
bzrlib/_rio_pyx.pyx:19:#python2.4 support
bzrlib/_walkdirs_win32.pyx:88:    # We can't just declare this as 'readonly' because python2.4 doesn't define
bzrlib/cethread.py:44:    # compatibility thunk for python-2.4 and python-2.5...
bzrlib/cleanup.py:163:    # As correct as Python 2.4 allows.
bzrlib/commands.py:841:    # for python 2.5 and later, optparse raises this exception if a non-ascii
bzrlib/diff.py:88:    # Special workaround for Python2.3, where difflib fails if
bzrlib/dirstate.py:3943:                    # on win32, python2.4 has e.errno == ERROR_DIRECTORY, but
bzrlib/dirstate.py:3944:                    # python 2.5 has e.errno == EINVAL,
bzrlib/errors.py:181:        # exceptions are old-style classes in python2.4 (but new in 2.5).
bzrlib/errors.py:721:        # Python 2.4 have to be old-style classes so properties don't work.
bzrlib/errors.py:3069:        # nb: in python2.4 socket.error doesn't have a useful repr
bzrlib/fifo_cache.py:43:        # Python2.5's has deque.remove, but Python2.4 does not
bzrlib/intset.py:194:          File "/usr/lib/python2.4/doctest.py", line 1243, in __run
bzrlib/library_state.py:53:        BzrLibraryState implements the Python 2.5 Context Manager protocol
bzrlib/osutils.py:289:# In Python 2.4.2 and older, os.path.abspath and os.path.realpath
bzrlib/osutils.py:915:    # Python 2.4 and later have os.urandom,
bzrlib/osutils.py:1181:    os.path.commonprefix (python2.4) has a bad bug that it works just
bzrlib/osutils.py:1642:      2) Windows, Python2.4, uses errno == ERROR_DIRECTORY (267)
bzrlib/osutils.py:1644:      3) Windows, Python2.5 uses errno == EINVAL and
bzrlib/plugins/launchpad/lp_registration.py:57:        # In python2.4 xmlrpclib.Transport is a old-style class, and does not
bzrlib/plugins/launchpad/test_register.py:102:    # Python 2.5's xmlrpclib looks for this.
bzrlib/pyutils.py:71:# +SKIP is not recognized by python2.4
bzrlib/remote.py:3250:    A replacement for extractall, which is not present in python2.4
bzrlib/repofmt/knitpack_repo.py:678:            # Python 2.4 does not permit try:finally: in a generator.
bzrlib/rio.py:127:        ##    value = str(value)           # XXX: python2.4 without L-suffix
bzrlib/tests/__init__.py:767:            # Python 2.4
bzrlib/tests/__init__.py:1368:            # On Win32 both 'dev' and 'ino' cannot be trusted. In python2.4 it
bzrlib/tests/__init__.py:1369:            # is 'dev' that varies, in python 2.5 (6?) it is st_ino that is
bzrlib/tests/ftp_server/medusa_based.py:115:            # (bialix 20070418) str(e) on Python 2.5 @ Windows
bzrlib/tests/ftp_server/medusa_based.py:156:                # (bialix 20070418) str(e) on Python 2.5 @ Windows
bzrlib/tests/http_server.py:195:        """Overrides base implementation to work around a bug in python2.5."""
bzrlib/tests/http_server.py:317:            # do beginning with python 2.4.3: abandon query
bzrlib/tests/test_errors.py:44:        Python 2.5 uses a slot for StandardError.message.
bzrlib/tests/test_errors.py:51:                'Requires Python 2.5 or later.')
bzrlib/tests/test_errors.py:512:        # python2.5 because that is a slot on the base Exception class
bzrlib/tests/test_http.py:2150:Server: SimpleHTTP/0.6 Python/2.5.2\r
bzrlib/tests/test_osutils.py:437:        # dereferenced) in Python 2.4.1 and earlier
bzrlib/transport/http/_urllib2_wrappers.py:635:        # header names, but only python2.5 urllib2 use title() to fix them just
bzrlib/transport/http/_urllib2_wrappers.py:636:        # before sending the request. And not all versions of python 2.5 do
bzrlib/transport/http/_urllib2_wrappers.py:995:        # FIXME: python 2.5 urlparse provides a better _parse_proxy which can
bzrlib/transport/http/_urllib2_wrappers.py:1547:    # but python-2.4 urllib2.Request insist on using capitalize()
bzrlib/transport/sftp.py:65:# Disable one particular warning that comes from paramiko in Python2.5; if
bzrlib/transport/sftp.py:71:# /var/lib/python-support/python2.5/paramiko/message.py:226: DeprecationWarning: integer argument expected, got float
bzrlib/tuned_gzip.py:102:    python 2.4 stock GzipFile write:
bzrlib/util/configobj/configobj.py:41:    # Python 2.2 does not have these
bzrlib/util/configobj/configobj.py:111:        """enumerate for Python 2.2."""
bzrlib/util/configobj/configobj.py:951:        retain compatibility with Python 2.2.
bzrlib/util/configobj/configobj.py:2154:                    # For Python 2.2 compatibility
bzrlib/xml_serializer.py:32:        # it's in this package in python2.5
doc/developers/code-style.txt:80:Bazaar supports Python from 2.4 through 2.6, and in the future we want to
doc/developers/code-style.txt:81:support Python 2.7 and 3.0.  Avoid using language features added in 2.5,
doc/developers/code-style.txt:91:* Don't use ``try/except/finally``, which is not supported in Python2.4,
doc/developers/code-style.txt:393:``Exception`` (which excludes system errors in Python2.5 and later) would
doc/developers/integration.txt:37:In Python 2.4 the ``with`` keyword is not supported and
doc/developers/plugin-api.txt:141:  #!/usr/bin/env python2.4
doc/developers/releasing.txt:213:       # Python version 2.0 is (2, 0, 0, 'final', 0)."  Additionally we use a
doc/developers/tortoise-strategy.txt:282:FWIW, with a Python process at each end, my P4 2.4G machine can achieve
doc/developers/ui.txt:124:good place to use them, but because python2.4 does not allow ``finally``
doc/developers/win32_build_setup.txt:46:   b) python 2.5.4 http://www.python.org/ftp/python/2.5.4/python-2.5.4.msi
doc/developers/win32_build_setup.txt:47:   c) python 2.4.4 (there is no Windows installer for 2.4.5 or 2.4.6)
doc/developers/win32_build_setup.txt:48:      http://www.python.org/ftp/python/2.4.4/python-2.4.4.msi
doc/developers/win32_build_setup.txt:73:   all-in-one installer is built using python 2.5. We will likely soon switch
doc/developers/win32_build_setup.txt:104:      Currently they only seem to offer PyQt 4.4.3 for python 2.5 and PyQt
doc/developers/win32_build_setup.txt:148:8) Fix distutils for the specific version of gcc. Distutils in python2.4.4 has
doc/en/admin-guide/introduction.txt:34:In general, Bazaar requires only Python_ 2.4 or greater and the cElementTree_
doc/en/admin-guide/introduction.txt:35:package (included in Python 2.5 and later) to run.  If you would *optionally*
doc/en/release-notes/bzr-0.1.txt:508:* testbzr requires python2.4, but can be used to test bzr running
doc/en/release-notes/bzr-0.1.txt:542:* Cope on Windows on python2.3 by using the weaker random seed.
doc/en/release-notes/bzr-0.1.txt:650:* Workaround for difflib bug in Python 2.3 that causes an
doc/en/release-notes/bzr-0.1.txt:734:* Fix time.localtime call to work with Python 2.3 (the minimum
doc/en/release-notes/bzr-0.11.txt:134:* Fixes to run on Python 2.5 (Brian M. Carlson, Martin Pool, Marien Zwart)
doc/en/release-notes/bzr-0.18.txt:37:* Work around python-2.4.1 inhability to correctly parse the
doc/en/release-notes/bzr-0.92.txt:183:  some other exceptions on Python 2.5.
doc/en/release-notes/bzr-1.17.txt:29:  api ``PyFrozenSet_New``. It turns out that python2.4 did not expose the
doc/en/release-notes/bzr-1.8.txt:104:* The C extensions now build on python 2.4 (Robert Collins, #271939)
doc/en/release-notes/bzr-1.9.txt:123:  for python2.4. (John Arbash Meinel, #277484)
doc/en/release-notes/bzr-2.1.txt:868:regression in python 2.4 compatibility in 2.1.0b2.  Since this regression
doc/en/release-notes/bzr-2.2.txt:437:  context manager in the Python 2.5 and above sense. The bzrlib base class
doc/en/release-notes/bzr-2.2.txt:921:This is a somewhat early second beta of the 2.2 series, to fix a python2.4
doc/en/release-notes/bzr-2.2.txt:960:* Fixed Python2.4 incompatibilities in the bzr2.2b1 source tarball.
doc/en/release-notes/bzr-2.4.txt:262:improvements. Support for python 2.4 and 2.5 has been dropped, many large
doc/en/release-notes/bzr-2.4.txt:694:* ``bzr-2.4`` has officially dropped support for python2.4 and python2.5.
doc/en/user-guide/installing_bazaar.txt:36:  1. If it is not installed already, install Python 2.4 or later.
doc/en/whats-new/whats-new-in-2.2.txt:289:  context manager in the Python 2.5 and above sense. The bzrlib base class
doc/en/whats-new/whats-new-in-2.4.txt:32:Dropping Python2.4 and Python2.5 support
profile_imports.py:126:            loc = scope_name.find('python2.4')
tools/generate_docs.py:30:    python2.4 generated-docs.py man
tools/generate_docs.py:31:    python2.4 generated-docs.py bash_completion
tools/http_client.py:56:# Note that (as of ubuntu python 2.4.1) every socket.connect() call
tools/win32/bzr.iss.cog:10:; # Python 2.5 compatibility code
tools/win32/bzr.iss.cog:16:; #/Python 2.5 compatibility code