Continue after prepare failure in tmt try

[lukaszachy]

Useful if machine needs tweaks before prepare can work, e.g. enable repos.
Fix: #2685

WDYT ? Error message needs tweaks (e.g write it in red...) but any objections against this behaviour change?

I often hit this if test requires something from beaker task library or crb isn't enabled in the image.

Pull Request Checklist

• implement the feature
• write the documentation
• extend the test coverage
• update the specification
• adjust plugin docstring
• modify the json schema
• mention the version
• include a release note

[happz]

The printing of the error does not feel right, how would show_exception() work for you? It should print out causes as well, and it can be told not to include tracebacks with the following patch:

diff --git a/tmt/utils/__init__.py b/tmt/utils/__init__.py
index ca322f9c..bb0f75e1 100644
--- a/tmt/utils/__init__.py
+++ b/tmt/utils/__init__.py
@@ -2775,6 +2775,7 @@ def render_exception(
 
 def show_exception(
         exception: BaseException,
+        traceback_verbosity: Optional[TracebackVerbosity] = None,
         include_logfiles: bool = True) -> None:
     """
     Display the exception and its causes.
@@ -2786,7 +2787,7 @@ def show_exception(
 
     from tmt.cli import EXCEPTION_LOGGER
 
-    traceback_verbosity = TracebackVerbosity.from_env()
+    traceback_verbosity = traceback_verbosity or TracebackVerbosity.from_env()
 
     def _render_exception(traceback_verbosity: TracebackVerbosity) -> Iterator[str]:
         yield ''

try:
    plan.prepare.go()
except GeneralError as error:
    tmt.utils.show_exception(
        error,
        traceback_verbosity=TracebackVerbosity.DEFAULT,
        include_logfiles=False
    )

It would have the advantage of reusing the existing error-logging capabilities of tmt. Maybe include_logfiles should be enabled, user probably does not care about traceback in terminal, but it might be useful to have them logged in log.txt.