It seem that something in the make install process is causing this issue, but I'm not sure what it is. The ruby -v I've indicated is the version of ruby used when compiling trunk. This occurs for me on Mac OSX 10.6.8. Let me know any specific information you need and I'll provide it as soon as possible.
Try following:
rm -rf /Users/chriswhite/Ruby/ruby-trunk
cd
./configure --prefix=/Users/chriswhite/Ruby/ruby-trunk --with-gcc=gcc-4.2
make all install
I tried this and got the same result. I notice that the source tree ruby and the ruby installed in the target directory are different sizes. I don't see strip being used, so I'm not sure what's causing this.
I also just noticed that if I use --enable-shared with ./configure, the library reference to the dylib disappears in the installed version, but remains in the source tree version:
SOLAR:~ chriswhite$ otool -L ~/Source/Repository/ruby/ruby ; otool -L ~/Ruby/ruby-trunk/bin/ruby
/Users/chriswhite/Source/Repository/ruby/ruby:
/Users/chriswhite/Ruby/ruby-trunk/lib/libruby.1.9.1.dylib (compatibility version 1.9.1, current version 1.9.1)
/usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 125.2.11)
/usr/lib/libobjc.A.dylib (compatibility version 1.0.0, current version 227.0.0)
/Users/chriswhite/Ruby/ruby-trunk/bin/ruby:
/usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 125.2.11)
/usr/lib/libobjc.A.dylib (compatibility version 1.0.0, current version 227.0.0)
SOLAR:~ chriswhite$
After some more in depth research, I realized that the issue was that a ruby executable existed in the toplevel source's bin/ directory which was overwriting the proper ruby executable. Since the file was not recreated after a clean build, this bug should be closed as invalid.
I would recommend however that the ruby in the toplevel directory get installed after all the files in bin/ just in case.