This has been fixed in the source files and will be included in the next build.
It appears that the source file for Bold no longer matches the GlyphOrderAndAliasDB_TT spec after this modification...
makeotf [Note] Converting source font 'Roman/Bold/font.ttf' to temporary Unix Type1 font file 'Roman/Bold/font.ttf.tmp'.
makeotf [Note] adding the style Bold from fontinfo keyword.
makeotf [Note] setting the DONT_USE_WIN_LINE_METRICS OS/2 fsSelection bit 7 from fontinfo keyword.
makeotf [Note] setting the WEIGHT_WIDTH_SLOPE_ONLY OS/2 fsSelection bit 8 from fontinfo keyword.
makeotf [Note] setting the OBLIQUE OS/2 fsSelection bit 9 from fontinfo keyword.
makeotf [Note] Writing options file Roman/Bold/current.fpr
makeotf [Note] Writing options file target/SourceCodePro-Bold-ttf.fpr
makeotf [Error] For TTF fonts, the GlyphOrderAndAliasDB file must preserve the original font glyph order, and use the same names as they are derived by the 'tx' tool. ../../GlyphOrderAndAliasDB_TT.
See issue #19 for discussion and pull request #21 for a fix to the above error in makeotf. (Apologies for spamming the bug tracker! :))
Fixed in revision 1.010