First Pass, unedited. If anyone besides myself ends up reading this please leave a comment and I will apply some polish.
Even with the SSH configuratoin stuff below setup correctly you still need to put your identity into each project-level
.git/config file and not rely on ~/.gitconfig. While obvious in hind-sight... The UI doesn't have an independment notion
of identity and because you are working on a local clone does not use identity information associated with origin. This
too makes sense as you are able to have multiple remotes associated with a given local repository. If you forget and notice a
commit with bad author information you can use git commit --amend --reset-author - though it may be that a normal ammend with
do this too...after you have added the [user] name & email variables to config.
C:/Users/<name>/.ssh/config - don't bother adding a config here...the one in /etc/ssh/ssh_config asserts host configuration precedence.
The default configuration also does not generate a known_hosts file, instead redirecting is to /dev/null
Within Windows the PortableGit* directory serves as the effective root of the Cygwin directory structure for GitHub for Windows.
Therein you will find /etc/ssh/ssh_config. The configurations in this file will supercede any matching configurations present in
/c/Users/<name>/.ssh/config. For this reason it will be necessary to remove the Host github.com entry; sepcifically the "IdentityFile" variable, so that changes made in ~/.ssh/config can take effect.
Note, on my Windows 7 installation (not positive on the exact configuration choices selected though) the location of the Cygwin PortableGit* directory is C:/Users/<name>/AppData/Local/GitHub/
Some kind of caching is going on since even removing the default ssh key from ~/.ssh still allows a ssh <host> to connect; using the wrong (and not longer existant) set of credentials)...
Said caching likely and reasonably comes from ssh-agent...not sure how the interaction there works but lets reset them and try again...
So indeed it does...needed to kill both ssh-agent process found when running ps ssh-agent. I figured one was linked to the shell
and the other linked to the GUI. I tried killing only the only logically linked to the GUI to no effect.
Or just ignore the last 3 paragraphs and read this [StackOverflow] (http://stackoverflow.com/questions/7927750/specify-an-ssh-key-for-git-push-for-a-given-domain) post...
Namely, specifying IdentitiesOnly yes in ~/.ssh/config so that the default Host entry IdentityFile is not prepended.
Actually, the interaction appears to be that the ssh-agent database was tried first, in its entireity, and then, if not found
the ~/.ssh directory was tried. Killing ssh-agent and using the original setup allowed the correct key to be found. Thus while
the identity files are indeed concatenated they are appended instead of prepended...
Actually, a combination of the two. Since the second entry setups another valid identity if the first IdentityFile is not present, or hasn't been loaded into ssh-agent, the second (default) IdentityFile will be provided.
So, for now I've setup separate host "aliases" in ~/.ssh/config and updated /etc/ssh/ssh_config to not assign a default IdentityFile for github.com. I'm partial to the supplied "Git Shell (Bash)" interface for cloning and then using the "Add" feature in the GUI to create an entry for the repository.