Is MRAN broken?

I have been trying to install packages from MRAN, specifically bsts amoung others. If I run:

install.packages(c("Boom","BoomSpikeSlab", "bsts"),repos = "https://mran.revolutionanalytics.com/snapshot/2016-01-01/")

I get the following output:

Warning in install.packages :
  URL 'https://mran.revolutionanalytics.com/snapshot/2016-01-01/bin/macosx/mavericks/contrib/3.3/PACKAGES.gz': status was '404 Not Found'

Warning in install.packages :
  URL 'https://mran.revolutionanalytics.com/snapshot/2016-01-01/bin/macosx/mavericks/contrib/3.3/PACKAGES': status was '404 Not Found'
Warning in install.packages :
  unable to access index for repository https://mran.revolutionanalytics.com/snapshot/2016-01-01/bin/macosx/mavericks/contrib/3.3:
  cannot download all files
Packages which are only available in source form, and may need compilation of C/C++/Fortran: ‘Boom’ ‘BoomSpikeSlab’ ‘bsts’
Do you want to attempt to install these from sources?
y/n:

I also get the same result when changing the repository location using options(). A simple solution would be simply to install from source as below:

install.packages(c("Boom","BoomSpikeSlab", "bsts"),repos = "https://mran.revolutionanalytics.com/snapshot/2016-01-01/",type = "source")

However what doesn't make sense is that, when you check the repository on your browser, the binaries appear to be available:

https://cran.r-project.org/web/packages/bsts/index.html (CRAN) https://mran.revolutionanalytics.com/snapshot/2016-01-01/web/packages/bsts/index.html (MRAN)

Additionally I would prefer not to have to compile the source code, especially as R's compiler is out of date...

Previous stack overflow questions have suggested this is because the repository is down, however this doesn't make sense as the binaries can be accessed through the browser. So is there an issue with MRAN, is there an issue with install.packages?

I should note I have tried executing this code in both RStudio and R through the terminal. Additionally, for reference, this is my system details:

platform       x86_64-apple-darwin13.4.0   
arch           x86_64                      
os             darwin13.4.0                
system         x86_64, darwin13.4.0        
status                                     
major          3                           
minor          3.2                         
year           2016                        
month          10                          
day            31                          
svn rev        71607                       
language       R                           
version.string R version 3.3.2 (2016-10-31)
nickname       Sincere Pumpkin Patch

Thanks in advance for the help.

Solution

I've now solved this problem. When calling from the MRAN repository using install.packages you need to capitalise "MRAN" part of the URL.

So this works:

install.packages("bsts", repos = "https://MRAN.revolutionanalytics.com/snapshot/2016-06-01/")

And this only works from source:

install.packages("bsts", repos = "https://mran.revolutionanalytics.com/snapshot/2016-06-01/")