Why? Because sometimes admins upgrade production servers (usually from CVS) to unwanted latest development version.
How? Tweak existing setup code to display warning page before upgrade if $previousversion < 2004090100.
See the included page.
I like that idea!! How many times have we had questions on the forums about "how do I go back?"
If my vote counts, I vote go for it!!
In seeing your topic, I just want to make a suggestion: I also accidentally upgraded to 1.5dev, by using cvs.
I wanted to upgrade my beta version of moodle 1.4, and went to the install page in order to see what the cvs command was. Then I did use the cvs update -dP, and the version installed was version 1.5dev.
I suggest that the instruction to update with cvs is changed to cvs update -dPr MOODLE_14_STABLE, where it says:
"Later, to update your local copy of Moodle to the current version in CVS you just need to go into your local moodle directory and type:
cvs update -dP"