Retain a username and password in TortoiseHG.

Stack Overflow has the answer as always:

1. Inside of the root of a project there will be an ".hg" folder. Go into this folder and open "hgrc" in Notepad.
2. Paths which look like this...
   http://www.example.com/whatever
   ...need to be doctored to look like this...
   http://foo:bar@www.example.com/whatever
   ...where foo is your username and bar is your password. (Yes, this is the same convention one used to FTP via the URL line in IE eight years ago.)