Export folder needs to not ignore .mbed files.

[Alex-EEE]

Description

Fixing a bug. .mbed is ignored in the high level .gitignore file. But .mbed is actually a needed file inside of tools/export. Even though the file is still in the main repo, since it's ignored now, you can easily lose it or remove it without seeing the change. Adding this .gitignore file here will add .mbed back into the tracked files for only this directory

Pull request type

[X ] Fix
[ ] Refactor
[ ] New target
[ ] Feature
[ ] Breaking change

[cmonr]

Interesting. Wondering why our export tests didn't catch this.
I'm also wondering what that .mbed file is used for since I only saw it referenced once in the entire repo, but I suppose that's a question for @theotherjimmy.

/morph build

[Alex-EEE]

Your export test will probably pass b/c the .mbed got into the repository somehow, probably before .mbed was added to the root .gitignore. However you won't ever be able to change that .mbed file b/c going forward git will ignore any changes you make to it. I noticed this issue b/c I'm maintaining a local fork, and it somehow got deleted in one of my merges of the latest mbed-os. Then I tried to export, and the python script most definitely fails if it can't find that .mbed file.

[mbed-ci]

Build : SUCCESS

Build number : 2027
Build artifacts/logs : http://mbed-os.s3-website-eu-west-1.amazonaws.com/?prefix=builds/6896/

Triggering tests

/morph test
/morph uvisor-test
/morph export-build
/morph mbed2-build

[mbed-ci]

Test : FAILURE

Build number : 1833
Test logs :http://mbed-os-logs.s3-website-us-west-1.amazonaws.com/?prefix=logs/6896/1833

[mbed-ci]

Exporter Build : SUCCESS

Build number : 1676
Build artifacts/logs : http://mbed-os.s3-website-eu-west-1.amazonaws.com/?prefix=builds/exporter/6896/

[theotherjimmy]

Good by me.

[cmonr]

Relaunching test due to an earlier no-disk-space-left issue.

/morph test

[mbed-ci]

Test : SUCCESS

Build number : 1900
Test logs :http://mbed-os-logs.s3-website-us-west-1.amazonaws.com/?prefix=logs/6896/1900