The 'BasicTest.cbp_BACK' contains the CodeBlocks project.
But it must not be used in this directory.
copy the content of this directory to
.../IDE/BasicTest/IDE_CB_Windows/* beside '.../src/BasicTest/IDE_CB...
or better copy as hard link using '+spawn....bat' to work with CodeBlocks in the IDE directory.
The '*.cbp_BACK' is / should be stored as '.../IDE/BasicTest/IDE_CB_Windows/*.cbp'

The reason is: do never merge sources and objects in the same folder tree. 
The CodeBlocks project creates its outputs (artefacts) beside the projekt directory,
thats why it should not be used on this position.

copy, maybe adapt and use '+clean_mkLink_build.bat' '+mklink_bin_tmpRAM.sh' to work if possible on a RAM disk.

After changes the content of the project file may be necessary to synchronized with this '*.cbp_BACK'

Information: 
A hard linked file is only one file on your hard disk, which is referred by more as one directory entries.
This is a concept given also on old UNIX systems, any time available on Linux, and introduced 
in Windows beginning with Windows-XP, but rarely documented. It is supported by MS Visual Studio 
and also Codeblocks, but often ordinary text editors break the hard link. 
Because there working approach were designed in times of DOS and older Windows versions.
Hard links were not broken on working approaches for files: __open - read - modify/write - close__. 
But text editors works often in the working approach __open - read - close__ and later
__open - write (create new) - close__. This creates a new file, non related to the original
and hence breaks the hard link.