A bunch of string literals in src/mongo/installer/msi/SConscript have embedded backslashes, since that's the path separator on Windows platforms. These use the python r'...' raw-string notation, to inhibit the normal backslash escape-code interpretation.

However, enterprisebase was apparently accidentally missed, despite containing path separator backslashes. This leads to the message SyntaxWarning: invalid escape sequence '\m' when parsing this SConscript file with the Python AST parser.

I think it's only ever worked because all the affected characters (m, d, e) aren't valid escape codes, and so get passed through unchanged (ie. by sheer fluke). It's been this way for a very long time, but I think it's still probably best to add the leading r.