python-sphinx embeds a timestamp of the build date into generated documentation by default.
This has been fixed upstream since sphinx 1.4
The manpages differ in the timestamp and python-sphinx (sphinx-build) was used to generate the manpages.
The configuration variable today can be set to a different (deterministic) value. The Makefiles often contain a SPHINXOPTS variable, that can be set and which is passed to sphinx-build.
Example for debian/rules:
SOURCE_DATE_EPOCH ?= $(shell date -d "$$(dpkg-parsechangelog -S Date)" +%s) BUILD_DATE=$(shell LC_ALL=C date -u "+%B %d, %Y" -d "@$(SOURCE_DATE_EPOCH)") ... make man -C docs/ SPHINXOPTS="-D today=\"$(BUILD_DATE)\""