Don't pass invalid ICE_CONFIG to Ice (fix #10051).

[bpindelski]

This PR fixes https://trac.openmicroscopy.org/ome/ticket/10051.

To test, follow the steps from the ticket, with a tiny modification:

• Start the server
• Login in via bin/omero login
• Set the ICE_CONFIG env var (export ICE_CONFIG=bin/omero sessions file``)
• Log out (bin/omero logout)
• Stop the server
• Try to start the server
• Verify that no error message appears

This should also work when ICE_CONFIG is set to any invalid file/directory.

[dominikl]

No error message, server starts fine, good to merge.

[joshmoore]

Makes sense to me. @bpindelski, did you happen to take a look at the interaction with the lines:

3b5c3848 components/tools/OmeroPy/src/omero/cli.py (jmoore           2008-05-27 14:11:41 +0000 1245)     # Modiying the run-time environment
3b5c3848 components/tools/OmeroPy/src/omero/cli.py (jmoore           2008-05-27 14:11:41 +0000 1246)     old_ice_config = os.getenv("ICE_CONFIG")
3b5c3848 components/tools/OmeroPy/src/omero/cli.py (jmoore           2008-05-27 14:11:41 +0000 1247)     os.unsetenv("ICE_CONFIG")

Guess to some extent it's suprising that ICE_CONFIG is set if unsetenv is called. But it might be that your solution of only unsetting if the file doesn't exist is more generally applicable.

@sbesson, that may just need to be something we look into later, but any comments before merging welcome.

[bpindelski]

@joshmoore The os.unsetenv was my initial implementation and it didn't work. Only the current approach seems to be doing the trick.

[joshmoore]

Interesting. Then there must be something I didn't understand about unsetenv. Merging, and @sbesson and I can keep in mind that this is perhaps a better long-term solution. Thanks!

[bpindelski]

--no-rebase