These variables only make sense in interactive bash session where we
always re-read .bashrc anyway.

Mostly due to ls...

Turns out that these need to be often repeated

At least on Fedora this is tmpfs

In case of 2 parameters, the wrapper will short-circuit if the files are
same.

Name function right in the first place, instead naming it wrong and
renaming it using alias.

*   More intuitive file naming,
*   setup simplified,
*   setup is now in script (vs. diff file),
*   removed unnecessary exec mode.

With calls like `git --version`, "--version" was passed to grep as its
own parameter.  This also affected git tab completion features.

Especially useful because of the dangetous git-am behavior and its
short name (easily confused with my often used alias `am`).