Eliminate ManifestError for wildcards matching 0 files.

Turns out that some (many?) wildcard LLManifest.path(wildcard) calls are "just
in case": sweep up any (e.g.) "*.tga" files there may be, but no problem if
there are none.
Change path() logic so it tries the next tree (source, artwork, build) if
either a specific (non-wildcard) filename doesn't exist, as now, OR if a
wildcard matches 0 files in the current tree. This continues to support "just
in case" wildcards, while permitting wildcards to work in the artwork and
build trees as well as the source tree.
Use a more specific exception than ManifestError for missing file. Only in
that case should we try the next tree. Any other ManifestError should
propagate.

indra/lib/python/indra/util/llmanifest.py

@@ -42,6 +42,11 @@
 import subprocess
 
 class ManifestError(RuntimeError):
+    """Use an exception more specific than generic Python RuntimeError"""
+    pass
+
+class MissingError(ManifestError):
+    """You specified a file that doesn't exist"""
     pass
 
 def path_ancestors(path):
@@ -604,16 +609,12 @@ def wildcard_regex(self, src_glob, dst_glob):
 
     def check_file_exists(self, path):
         if not os.path.exists(path) and not os.path.islink(path):
-            raise ManifestError("Path %s doesn't exist" % (os.path.abspath(path),))
+            raise MissingError("Path %s doesn't exist" % (os.path.abspath(path),))
 
 
     wildcard_pattern = re.compile(r'\*')
     def expand_globs(self, src, dst):
         src_list = glob.glob(src)
-        # Assume that if caller specifies a wildcard, s/he wants it to match
-        # at least one file...
-        if not src_list:
-            raise ManifestError("Path %s doesn't exist" % (os.path.abspath(src),))
         src_re, d_template = self.wildcard_regex(src.replace('\\', '/'),
                                                  dst.replace('\\', '/'))
         for s in src_list:
@@ -646,13 +647,23 @@ def try_path(src):
                 else:
                     count += self.process_file(src, dst)
             return count
-        try:
-            count = try_path(os.path.join(self.get_src_prefix(), src))
-        except ManifestError:
+
+        for pfx in self.get_src_prefix(), self.get_artwork_prefix(), self.get_build_prefix():
             try:
-                count = try_path(os.path.join(self.get_artwork_prefix(), src))
-            except ManifestError:
-                count = try_path(os.path.join(self.get_build_prefix(), src))
+                count = try_path(os.path.join(pfx, src))
+            except MissingError:
+                # If src isn't a wildcard, and if that file doesn't exist in
+                # this pfx, try next pfx.
+                count = 0
+                continue
+
+            # Here try_path() didn't raise MissingError. Did it process any files?
+            if count:
+                break
+            # Even though try_path() didn't raise MissingError, it returned 0
+            # files. src is probably a wildcard meant for some other pfx. Loop
+            # back to try the next.
+
         print "%d files" % count
 
     def do(self, *actions):