Explain why we think a release has not been fully installed

Change from

           INFO     Showing status of release dev-23a in                                   mpsd_software.py:1029
                    /Users/fangohr/git/mpsd-software-manager/build
           DEBUG    Looking for files in                                                   mpsd_software.py:1045
                    /Users/fangohr/git/mpsd-software-manager/build/dev-23a/m2/spack
           ERROR    MPSD release 'dev-23a' has not been completely installed.              mpsd_software.py:1046`

to

[07:35:02] INFO     Showing status of release dev-23a in                                   mpsd_software.py:1029
                    /Users/fangohr/git/mpsd-software-manager/build
           INFO     Could not find directory                                               mpsd_software.py:1045
                    /Users/fangohr/git/mpsd-software-manager/build/dev-23a/m2/spack.
           ERROR    MPSD release 'dev-23a' has not been completely installed.

requested review from @akarnad

approved this merge request

merged

mentioned in commit 277bdca8