Use git to generate version info instead of bzr.

Instead of bzr version-info --python, use git describe --tags. We drop
the build date here because it wasn't current anyway (it was only
updated when the bzr version changed).

seeds/pycorn/Makeppfile

@@ -17,10 +17,10 @@ $(phony always):
 
 ifndef USE_BINARIES
 stamp-version: always
-	bzr version-info --custom --template "{date} {revno} {revision_id} {branch_nick}" > stamp-version
+	git rev-parse HEAD > $(output)
 
 frozen/bootstrap/version.py: stamp-version : signature md5
-	bzr version-info --python > $(output)
+	&printf -f -o $(output) "GIT_VERSION = '%s'\\n" $(shell git describe --tags)
 
 frozen.c: freeze.py $(FREEZEDEPS)
 	$(PYTHON) freeze.py $(output) $(FREEZEDIRS)

seeds/pycorn/frozen/bootstrap/__init__.py

@@ -21,11 +21,10 @@
 from _metalmem import membuf
 
 from bootstrap.mini_zipimport import MiniZipImport
-from bootstrap.version import version_info
+from bootstrap.version import GIT_VERSION
 
 # Print version info/banner
-print 'Pycorn r%s' % version_info['revno'], '(Python %s.%s.%s)' % sys.version_info[0:3],
-print '(built %s)' % version_info['build_date']
+print 'Pycorn %s' % GIT_VERSION, '(Python %s.%s.%s)' % sys.version_info[0:3]
 
 # Clear existing path, which is useless
 del sys.path[:]