Re: http getpass function in msysgit

 - If you look at an environment, why check terminal at all?  If the
  calling application wants to specify "here is the way to ask the user
  for a password" with it, why not use it unconditionally?

I just worry about user set such environment accident. Learn it from  OpenSSH.
Unconditional is okay for me.

 - Why is it HTTP_ASKPASS?  If other codepaths (e.g. "ssh passphrase",
  "svn password") that do not have anything to do with HTTP transfer also
  wants that feature,

You can choose environment name you like. I choose HTTP_ASKPASS just
because getpass only used at http.c
ssl_cert_password = getpass("Certificate Password: ");

OpenSSH is separated application and use own SSH_ASKPASS to ask password ...

May GIT_ASKPASS is optional name.

 wouldn't it be easier for the users to specify one
  single "password dialog" helper program, that is launched by various
  parts of git, and ask "I need the HTTP password to access li.org", "I
  need to unlock the ssh key for fl@li.org", etc?

It is nice to use one dialog for all cases. git-svn also have the same problem.