rhg: add a test for --rev with a hex changeset ID

And fix error message formatting

Differential Revision: https://phab.mercurial-scm.org/D9478

rust/rhg/src/commands/cat.rs

@@ -70,7 +70,7 b' fn map_rev_error(rev: &str, err: CatRevE'
             )),
             CatRevErrorKind::InvalidRevision => CommandErrorKind::Abort(Some(
                 utf8_to_local(&format!(
-                    "abort: invalid revision identifier{}\n",
+                    "abort: invalid revision identifier {}\n",
                     rev
                 ))
                 .into(),

rust/rhg/src/commands/files.rs

@@ -85,7 +85,7 b' fn map_rev_error(rev: &str, err: ListRev'
             ListRevTrackedFilesErrorKind::InvalidRevision => {
                 CommandErrorKind::Abort(Some(
                     utf8_to_local(&format!(
-                        "abort: invalid revision identifier{}\n",
+                        "abort: invalid revision identifier {}\n",
                         rev
                     ))
                     .into(),

tests/test-rhg.t

@@ -116,6 +116,26 b' Cat copied file should not display copy '
   $ rhg cat -r 1 copy_of_original
   original content
 
+Specifying revisions by changeset ID
+  $ hg log
+  changeset:   1:41263439dc17
+  tag:         tip
+  user:        test
+  date:        Thu Jan 01 00:00:00 1970 +0000
+  summary:     add copy of original
+  
+  changeset:   0:1c9e69808da7
+  user:        test
+  date:        Thu Jan 01 00:00:00 1970 +0000
+  summary:     add original
+  
+  $ rhg files -r 41263439dc17
+  abort: invalid revision identifier 41263439dc17
+  [255]
+  $ rhg cat -r 41263439dc17 original
+  abort: invalid revision identifier 41263439dc17
+  [255]
+
 Requirements
   $ rhg debugrequirements
   dotencode