Analysis of the problem described here, using mingw-get's dependency tracing mode
$ mingw-get --trace=0x0200 install "mingw32-gcc=4.7.2-1" 2>&1 | tee trace-5.log
reveals that dependency resolution is failing for libgcc-4.7.2-1.dll-1 because the constraints specified when resolving the requirement for the gcc-core package appear to be subsequently ignored, when recursive evaluation of its further dependency on binutils causes re-evaluation of the libgcc dependency, with a less constrained specification.
This results in installation of the wrong version of the libgcc package, with consequent payload conflicts due to package reorganization, and probable malfunction of the installed application suite.
Not an ultimate solution, but moving the
libgcc-dllrequirement to last place in thegcc-core-bindependency list does appear to mitigate the issue.