When using the -r command and running from a remote repository, nextflow does not properly pull from the specified revsion before attempting to run the script

Steps to reproduce:
1. Run a test on the master branch
`nextflow run  hydriniumh2/nextflow_issue_233 -r master`
Result:
	Runs correctly
2. Try to run a test on the test_branch
`nextflow run hydriniumh2/nextflow_issue_233 -r test_branch`
Result: 
N E X T F L O W  ~  version 19.04.1
Missing project main script: [USER PATH]/.nextflow/assets/hydriniumh2/nextflow_issue_233/foo.nf
3. Try running the exact same command again, no changes:
`nextflow run hydriniumh2/nextflow_issue_233 -r test_branch`
Result:
	Runs correctly