raise error when unknown 'install_type' is used in Tarball easyblock + fix log messages

[boegel]

@lexming follow-up for #1989

• we shouldn't silently ignore the use of an unknown 'install_type' value, it should raise an error instead

• order of name/dir in log message is fixed, was:

  == 2020-04-30 10:26:00,206 tarball.py:114 INFO Wiping KNIME and copying tarball contents of /work/maintainers/CO7/broadwell/software/KNIME/3.6.2 into it...
  

  now:

  == 2020-04-30 10:28:36,328 tarball.py:111 INFO Copying tarball contents of KNIME into /work/maintainers/CO7/broadwell/software/KNIME/3.6.2 after wiping it...
  

[lexming]

Testing with easybuilders/easybuild-framework#3310

Successful test using tarball and install_type=subdir with easyconfig https://gist.github.com/lexming/61ea21f0add35b4d15c00e0deba34311

Log of the build: https://gist.github.com/lexming/8d2037338c4b365dcbae58b83c3484de

[lexming]

Testing with easybuilders/easybuild-framework#3310

FAILED test using tarball and install_type=merge with easyconfig https://gist.github.com/lexming/dd7a20aaa63ab24751d0f83c770d0559

Log of the build: https://gist.github.com/lexming/156e9ab54a373612a5142d49c66f1480

The reason for the failure is that there is a broken symlink at %(builddir)s/Alpha/20190607/foss-2019b-Python-2.7.16/thekswenson-alpha-3139d8186403/pyinclude
This broken symlink is not an issue with current implementation in develop.

[boegel]

@lexming That use case should be fixed now in easybuilders/easybuild-framework#3310 (also covered by the enhanced tests)

[lexming]

Testing with easybuilders/easybuild-framework#3310 (easybuilders/easybuild-framework@3c80fef)

SUCCESSFUL test with install_type=subdir using easyconfig https://gist.github.com/lexming/61ea21f0add35b4d15c00e0deba34311
Log: https://gist.github.com/lexming/ff33bb00a043728bc94385967d4a86b8
Result: each component is installed in its own subfolder

SUCCESSFUL test with install_type=merge using easyconfig https://gist.github.com/lexming/1d6a1eed0de99a77d8aecd0ad6aa8e92
Log: https://gist.github.com/lexming/e688fd147cdceded708c7881f9ba51d1
Result: the contents of all three components are properly merge in the installation directory

SUCCESSFUL test with install_type=potato using easyconfig https://gist.github.com/lexming/6fe5df2dcf43db787939c945a4874369
Log: https://gist.github.com/lexming/0e3361a0301a0d55a88140df35f81e51
Result: the build is stopped with an error message due to the unsupported install_type

SUCCESSFUL test without install_type using easyconfig https://gist.github.com/lexming/c646484ee0f3c858011bbdd1d9695d50
Log: https://gist.github.com/lexming/60b1f9d5d92e416319cf319c8ce66e31
Result: the installation directory only has the contents of the last component.
This test covers all existing easyconfig as this is the default behaviour of tarball.

[lexming]

LGTM

I would just remove the Ignoring part from the error message as it is no longer the case.

[lexming]

LGTM

[lexming]

Going in, thanks for the fixes @boegel !