Mention in docs what determines a succeeded pipeline (#282)

* marge.app: print stdout/stderr for Exceptions

This fixes the following problem: bot executes various commands with the
`timeout` arg, and may throw a TimeoutExpired exception.  However,
printing TimeoutExpired exception won't print stdout and stderr.

Due to absence of stdout/stderr anywhere in the output this confuses and
looks like the command didn't manage to get too far in execution. Like
for example, as if the remote server didn't respond, making a `git
clone` to time out.

Signed-off-by: Konstantin Kharlamov <[email protected]>

* README.md: mention what determines whether marge-bot waits for pipeline

Fixes: #281

Signed-off-by: Konstantin Kharlamov <[email protected]>

README.md

@@ -41,6 +41,10 @@ message on the merge-request, so you'll get notified. Marge-bot can handle an
 adversarial environment where some developers prefer to merge their own changes,
 so the barrier for adoption is really low.
 
+Whether marge-bot will or not wait for pipeline to succeed depends on the value of "✓
+Pipelines must succeed" checkbox in your repo. It is available in all Gitlab
+versions, so should not be a barrier.
+
 Since she is at it, she can optionally provide some other goodies like tagging
 of commits (e.g. `Reviewed-by: ...`) or preventing merges during certain hours.
 
@@ -240,7 +244,7 @@ docker run --restart=on-failure \
   --config-file=/configuration/marge-bot-config.yaml
 ```
 
-By default docker will use the `latest` tag, which corresponds to the latest 
+By default docker will use the `latest` tag, which corresponds to the latest
 stable version. You can also use the `stable` tag to make this more explicit.
 If you want a development version, you can use the `master` tag to obtain an
 image built from the HEAD commit of the `master` branch. Note that this image

marge.app

@@ -1,3 +1,12 @@
 #!/usr/bin/env python3
 import marge.app
-marge.app.main()
+
+try:
+    marge.app.main()
+except Exception as e:
+    print('Exception occured')
+    if hasattr(e, 'stdout'):
+        print(f'stdout was: {e.stdout}')
+    if hasattr(e, 'stderr'):
+        print(f'stderr was: {e.stderr}')
+    raise