More verbose errors for NoManifestExceptions.

The old "manifest required for this command -- please run
init" is replaced by a more helpful message that lists the
command repo was trying to execute (with arguments) as well
as the str() of the NoManifestException. For example:

> error: in `sync`: [Errno 2] No such file or directory:
> 	'path/to/.repo/manifests/.git/HEAD'
> error: manifest missing or unreadable -- please run init

Other failure points in basic command parsing and dispatch
are more clearly explained in the same fashion.

Change-Id: I6212e5c648bc5d57e27145d55a5391ca565e4149

1 files changed, 16 insertions, 11 deletions

diff --git a/main.py b/main.py
index 36617762..72fb39b0 100755
--- a/main.py
+++ b/main.py
@@ -129,8 +129,15 @@ class _Repo(object):
             file=sys.stderr)
       return 1
 
-    copts, cargs = cmd.OptionParser.parse_args(argv)
-    copts = cmd.ReadEnvironmentOptions(copts)
+    try:
+      copts, cargs = cmd.OptionParser.parse_args(argv)
+      copts = cmd.ReadEnvironmentOptions(copts)
+    except NoManifestException as e:
+      print('error: in `%s`: %s' % (' '.join([name] + argv), str(e)),
+        file=sys.stderr)
+      print('error: manifest missing or unreadable -- please run init',
+            file=sys.stderr)
+      return 1
 
     if not gopts.no_pager and not isinstance(cmd, InteractiveCommand):
       config = cmd.manifest.globalConfig
@@ -146,15 +153,13 @@ class _Repo(object):
     start = time.time()
     try:
       result = cmd.Execute(copts, cargs)
-    except DownloadError as e:
-      print('error: %s' % str(e), file=sys.stderr)
-      result = 1
-    except ManifestInvalidRevisionError as e:
-      print('error: %s' % str(e), file=sys.stderr)
-      result = 1
-    except NoManifestException as e:
-      print('error: manifest required for this command -- please run init',
-            file=sys.stderr)
+    except (DownloadError, ManifestInvalidRevisionError,
+        NoManifestException) as e:
+      print('error: in `%s`: %s' % (' '.join([name] + argv), str(e)),
+        file=sys.stderr)
+      if isinstance(e, NoManifestException):
+        print('error: manifest missing or unreadable -- please run init',
+              file=sys.stderr)
       result = 1
     except NoSuchProjectError as e:
       if e.name: