%{ } macros in spec files are expanded in comments. This gives unexpected effects if the substitution text has multiple lines (like %{_configure}
I'd think this is the expected behavior, in case macro expansions are needed in the comments, though it's seldom used. Does escaping the macro name using the form "%%{macro_name}" not give the desired text?
A .spec line like # %{_configure} doesn't work will expand to # [goobledygook] [more blah] doesn't work and this will yield a error message from sh ("EOF found while looking for `''"), which is at first sight entirely unrelated to the .spec file. The content of comments should be ignored, and expanding in a comment should have no effect, by definition, as far as I'm concerned. Either that or, all %{} macros should be on a single line. If this is a useful feature, then I'm little red ridinghood.
And I'm the Big Bad Wolf :-) Add the extra % ...
I'm sure the workaround you've mentioned will work, but doesn't it seem odd to not ignore the comments? perhaps rather than being marked resolved, this should be changed to an enhancement req, marked low priority, and shuffled to the bottom of the pile??