Where is sp_MSrepl_getpublisherinfo in SQL Server?
So after more research I found that sys.sp_MSrepl_getpublisherinfo lives in a database named mssqlsystemresource, which lives in Sql Server's binn folder. This database is invisible to SSMS, but you can copy and attach it as a different name to have full access. This process is described here:

http://www.sqlnewsgroups.net/sqlserver/t21348-browse-mssqlsystemresource-mdf-sql-servers-resource-database.aspx

I have copied that text here, in case that page goes away in the future:


  Giving credit where credit is due, I found the following info I am
  about to  post at the following location:  
  
  http://web.archive.org/web/20150407042809/http://www.aspfaq.com/sql2005/show.asp?id=28
  
  Since the engine has hooks that hide the mssqlsystemresource database
  from  users, you don't have direct access to it through the GUI.
  
  However, there is a way around this: 
  
  
  Determine where the system databse files live, and keep this path handy: 

USE master
GO
SELECT REPLACE(filename, 'master.mdf', '') 
  FROM sys.sysfiles 
 WHERE fileid = 1

  Stop the SQL Server service; 
  Copy the files mssqlsystemresource.*df -> resource_copy.*df.  NOTE: do not rename or remove the mssqlsystemresource files! 
  Start the SQL Server service; 
  Run the following code in a new query window: 

EXEC sp_attach_db 
  'Resource_Copy', 
  '&lt;path from above&gt;resource_copy.mdf', 
  '&lt;path from above&gt;resource_copy.ldf'

  Now, the system will no longer identify this database as a "special"  database 
  You can easily scan through the names of system objects that might  otherwise be unknown (and browse any code associated with these
  objects) from  a GUI (like SQL Server Management Studio).