Report subprocess exit code when invocation fails

[pytoxbot]

• Bitbucket: https://bitbucket.org/hpk42/tox/issue/192
• Originally reported by: @mgedmin
• Originally created at: 2014-09-26T13:38:03.984

Story: A Jenkins job running tox failed in the 'pip install' step, without a clear error message. After some headscratching I decided to look at dmesg and saw that the server ran out of memory and the OOM killer decided to kill some processes.

Now if tox reported actual exit statuses instead of just saying "invocation failed", I might've seen that pip did not exit with an error code but rather was killed by a signal. That would've been a useful Clue to have.

[pytoxbot]

Original comment by @hpk42

Report subprocess exit code when invocation fails

Fixes #192

→ <<cset 25efae2240bf>>

[pytoxbot]

Original comment by @mgedmin

Does this look about right?

diff -r 69a69d68fc46 tox/_cmdline.py
--- a/tox/_cmdline.py   Thu Sep 25 15:43:21 2014 +0200
+++ b/tox/_cmdline.py   Fri Sep 26 15:21:06 2014 +0300
@@ -95,9 +95,9 @@
         try:
             popen = self._popen(args, cwd, env=env,
                                 stdout=f, stderr=STDOUT)
-        except OSError:
-            self.report.error("invocation failed, args: %s, cwd: %s" %
-                              (args, cwd))
+        except OSError as e:
+            self.report.error("invocation failed (errno %d), args: %s, cwd: %s" %
+                              (e.errno, args, cwd))
             raise
         popen.outpath = outpath
         popen.args = [str(x) for x in args]
@@ -118,8 +118,8 @@
         if ret:
             invoked = " ".join(map(str, popen.args))
             if outpath:
-                self.report.error("invocation failed, logfile: %s" %
-                                  outpath)
+                self.report.error("invocation failed (exit code %d), logfile: %s" %
+                                  (ret, outpath))
                 out = outpath.read()
                 self.report.error(out)
                 if hasattr(self, "commandlog"):

If yes, I'll fix up the tests and submit a proper PR.

[pytoxbot]

Original comment by @hpk42

Agreed, care to submit a PR?