[fpc-pascal] Using other fpc installation

[kapibara]

For debugging reasons I have installed fpc 2.6.4 on Debian so I can 
compile some old SVN revisions, number 32959 for example.

I want to use the fp editor to run the test, but it seems as the 
"systemic" 2.6.4 is being used for compiling instead of the SVN version. 
The bug doesn't show up in 2.6.4, only in some 2.7.1 revisions and 
later. How can I make sure the SVN version is used and not the systems 
2.6.4?

The following paths was added to fp editor in Options->Units:

/home/roger/fpc/fpc_svn/lib/fpc/2.7.1/unitsx86_64-linux
/home/roger/fpc/fpc_svn/lib/fpc/2.7.1/unitsx86_64-linux/*
/home/roger/fpc/fpc_svn/lib/fpc/2.7.1/unitsx86_64-linux/rtl

Also, both the directories of fpc and ppcx64 was added to the path from 
commandline:

PATH=home/roger/fpc/fpc_svn/bin:/home/roger/fpc/fpc_svn/compiler:/usr/local/bin:/usr/bin:/bin
export 
PATH=home/roger/fpc/fpc_svn/bin:/home/roger/fpc/fpc_svn/compiler:/usr/local/bin:/usr/bin:/bin

Despite the path, if I run "which fpc" from commandline I get 
"usr/bin/fpc" anyway. How is that possible when that fpc is not in the 
path?