Why BitBucket Pipelines Caches not caches dotfiles on root folder

[xicond]

Hi,

I planned to saved a commit ID in cache so that I know the cache point

like:

git rev-parse HEAD > vendor/.commit

then I put cache definition like

definitions:
  caches:
    vendor: vendor

But seems the .commit not found on next pipeline execution, is that the expected behavior ? 

[xicond]

Sorry, my mistake on command

Some of my step mistakenly put in wrong folder