stage_install fails if Fusion is installed

[tst-lsavoie]

Describe the bug

If you install Fusion using the install_fusion.sh script and then run the stage_install phase of the build again, it will fail with many error messages similar to the following:

find: '/tmp/fusion_os_install/common/opt/google/qt/lib': No such file or directory
Cannot find libfreetype.so.6 for fusion /tmp/fusion_os_install/fusion/opt/google/bin/mapdbgen

Despite the errors, you can continue to re-install Fusion (and optionally server as well), and both Fusion and Server seem to operate correctly.

To Reproduce

1. Build Open GEE on Ubuntu 16.04: https://github.com/google/earthenterprise/blob/master/earth_enterprise/BUILD.md
2. Install Open GEE on the same machine: https://github.com/google/earthenterprise/wiki/Install-Fusion-or-Earth-Server
3. Run the build steps again. The stage_install step will fail.

If you continue from this point and install Fusion and Server, everything seems to work correctly.

Expected behavior

The stage_install step does not fail, even if Fusion is installed.

Environment

This has been observed on Ubuntu 16.04. It is uncertain if it occurs on other platforms.

This does not occur with RPM upgrades.

This happens when installing Open GEE 5.3.7+