Hello, this is a problem that is only visible in particular RPM package build environment.
In my case, it is Centos 5 distribution used under Open Build Service.

The RPM package build process occurs under directory "/usr/src/redhat/build/<package name>/", e.g. "/usr/src/redhat/build/tqca-14.0.1/" in my example.

The "./configure" script for this package invokes a "tqmake" command to generate a Makefile from the "qca.pro" file.

I simply run command:
  ./configure  --prefix=/usr  --qtdir=/usr --debug

Expected result: the various "install" targets in Makefile should refer to "/usr" directory, as specified on the command line.

Actual result: the "install" targets refer to "../../../.." directory, which is actually the relative path from "/usr/src/redhat/build/tqca-14.0.1" to "/usr".

E.g, when I expect to have something in Makefile like:
  $(INSTALL_FILE) "$(TARGET)" "$(INSTALL_ROOT)/usr/lib/$(TARGET)"
I have instead:
  $(INSTALL_FILE) "$(TARGET)" "$(INSTALL_ROOT)../../../../lib/$(TARGET)"


Then, when I run the commands:
  make
  make install INSTALL_ROOT="/usr/src/redhat/BUILDROOT/tqca-14.0.1"

the "install" target fails because the target directory is invalid.

This does NOT occur when the build directory is located anywhere outside "/usr" folder, which happens on all other distributions.

I'm not sure if that absolute-to-relative path conversion in tqmake is normal or not. But it causes FTBFS in this particular case.