Going to the previous working directory (`cd -`) does not behave as expected

[SuperJappie08]

While learning colcon for ROS 2 (as migrating from ROS 1).
I expected to colcon_cd to work like the ROS 1 roscd which allows for the following:

you:~/some_path$ roscd SOME_PACKAGE
you:/path/to/SOME_PACKAGE$ cd - # Return to previous PWD
you:~/some_path$ 

This was allowed since roscd only uses cd just before returning, allowing to use this default mechanism of cd.

However, when using colcon_cd the result is as follows:

you:~/some_path$ colcon_cd SOME_PACKAGE
you:/path/to/SOME_PACKAGE$ cd -
you:/path/to$ # Not where I expected to end up 

As a result of some digging in the source, this is the result of cd-ing multiple times.
Looking at the cd documentation, this could possibly be changed by setting the OLDPWD environment variable, which is used to store the old path.

EDIT: I can make a PR for this if this change is desired.

[mjcarroll]

EDIT: I can make a PR for this if this change is desired.

That would be fantastic.

[SuperJappie08]

After further inspection, this error only occurs when going to packages not in the current working directory, but on the _colcon_cd_root

[SuperJappie08]

Currently, I have a draft PR (#28) , which resolves the behavior.

However, the cd history, still gets erased when the package is not found.
Should I also fix that?

[SuperJappie08]

I also fixed the package not found case.