What happened to the -e option for pip?

The pip documentation mentions -e option to pip, and this is also used on some BuildBot developer 'getting started' notes. However, I have pip 1.0.1 and that running:

pip -e master

reports

Usage: pip COMMAND [OPTIONS]

pip: error: no such option: -e

Version 1.0.1 of pip seems to be the latest, in that running pip to upgrade its开发者_StackOverflow社区elf does not download a newer version. What happened to the -e option?

It's still there! But, -e is an option only to pip install, not to pip itself.

$ pip install -e
Usage: /usr/local/bin/pip install [OPTIONS] PACKAGE_NAMES...

/usr/local/bin/pip install: error: -e option requires an argument