installFromYum: give more detailed error messages on gpg errors

repository.py

@@ -830,15 +830,43 @@ def installFromYum(targets, mounts, progress_callback, cachedir):
         rv = p.wait()
         stderr.seek(0)
         stderr = stderr.read()
+        gpg_error_message = None
         if stderr:
             logger.log("YUM stderr: %s" % stderr.strip())
 
+            if ' in import_key_to_pubring' in stderr:
+                gpg_error_message = "Signature key import failed"
+            # add any other instance of uncaught GpgmeError before this like
+            elif 'gpgme.GpgmeError: ' in stderr:
+                gpg_error_message = "Cryptography-related yum crash"
+
+            elif re.search("Couldn't open file [^ ]*/repodata/repomd.xml.asc", stderr):
+                # would otherwise be mistaken for "pubring import" !?
+                gpg_error_message = "No signature on repository metadata"
+            elif 'repomd.xml signature could not be verified' in stderr:
+                gpg_error_message = "Repository signature verification failure"
+
+            else:
+                match = re.search("Public key for ([^ ]*.rpm) is not installed", stderr)
+                if match:
+                    gpg_error_message = "Missing key for %s" % (match.group(1),)
+                match = re.search("Package ([^ ]*.rpm) is not signed", stderr)
+                if match:
+                    gpg_error_message = "Package not signed: %s" % (match.group(1),)
+                match = re.search(r" ([^ ]*): \[Errno [0-9]*\] No more mirrors to try", stderr)
+                if match:
+                    # rpm not found or corrupted/re-signed/etc
+                    gpg_error_rpm_not_found = match.group(1)
+                    gpg_error_message = "Cannot find valid rpm for %s" % (match.group(1),)
+
         if rv:
             if rv > 0:
                 logger.log("Yum exited with %d" % rv)
             else:
                 logger.log("Yum killed by signal %d" % -rv)
-            raise ErrorInstallingPackage("Error installing packages")
+            if gpg_error_message is None:
+                gpg_error_message = "Error installing packages"
+            raise ErrorInstallingPackage(gpg_error_message)
 
         shutil.rmtree(os.path.join(mounts['root'], cachedir))