Error with TortoiseHg push to a remote computer

[casem]

Hello,

I am using TortoiseHg 3.0.0 on Windows 8; I also have Python 3.4.0 
installed. I push my repository to several remote locations using the 
ssh protocol. For one remote computer, I get an error. However, if I run 
the command with --verbose and then copy the exact ssh command that 
TortoiseHg uses into Cygwin (Cygwin details below), I can use that 
command successfully independently of TortoiseHg.

**FAILS on remote computer (must authenticate with password)**
TortoiseHg > Sync > hg push 
ssh://user@remote.computer.edu//$HOME/repository

Gives the following outputs (among others):
running ssh user at remote.computer.edu "hg -R /$HOME/repository serve 
--stdio"
...
remote: debug1: Authentications that can continue: 
publickey,gssapi-with-mic,password
remote: debug1: Next authentication method: password
remote: debug1: read_passphrase: can't open /dev/tty: No such device or 
address


**SUCCEEDS on bitbucket (whether authenticating with password or ssh 
key)**
TortoiseHg > Sync > hg push ssh://hg@bitbucket.org/user/repository/


**SUCCEEDS on remote computer outside of TortoiseHg (authenticating with 
password)**
ssh user at remote.computer.edu "hg -R /$HOME/repository serve --stdio"


Cygwin details
Cygwin version: 1.7.29(0.272/5/3) x86_64
openssh package: 6.6.1p1-1


I've tried googling this error in relation to Cygwin, openssh, on the 
forum for the remote computer, and looking through the Mercurial mailing 
list, but I haven't been able to solve this error. Specifically, I can't 
figure out why I get the error only when using TortoiseHg and only when 
I push to that particular remote destination. Any ideas appreciated.

Thanks,
Marianne