dispatch: error out on invalid -R path even if optionalrepo (issue4805) (BC)

Before this patch, repo could be set to None for wrong -R. It's okay for
commands that can reject repo=None, but the command server have a problem
because:

 - it accepts repo=None for "unbound" mode
 - and it reenters dispatch() where repo object is created for cwd by default

Test outputs are changed because the error is detected earlier. I think new
message is better than ".hg not found".

mercurial/dispatch.py

@@ -890,6 +890,8 b' def _dispatch(req):'
             except error.RequirementError:
                 raise
             except error.RepoError:
+                if rpath and rpath[-1]: # invalid -R path
+                    raise
                 if cmd not in commands.optionalrepo.split():
                     if (cmd in commands.inferrepo.split() and
                         args and not path): # try to infer -R from command args

tests/test-clone.t

@@ -1020,7 +1020,7 b" Test that auto sharing doesn't cause fai"
   $ hg -R a id -r 0
   acb14030fe0a
   $ hg id -R remote -r 0
-  abort: there is no Mercurial repository here (.hg not found)
+  abort: repository remote not found!
   [255]
   $ hg --config share.pool=share -q clone -e "python \"$TESTDIR/dummyssh\"" a ssh://user@dummy/remote
   $ hg -R remote id -r 0

tests/test-commandserver.t

@@ -589,6 +589,15 b' start without repository:'
   000000000000 tip
 
 
+don't fall back to cwd if invalid -R path is specified (issue4805):
+
+  $ cd repo
+  $ hg serve --cmdserver pipe -R ../nonexistent
+  abort: repository ../nonexistent not found!
+  [255]
+  $ cd ..
+
+
 unix domain socket:
 
   $ cd repo

tests/test-ssh-bundle1.t

@@ -43,14 +43,14 b' configure for serving'
 repo not found error
 
   $ hg clone -e "python \"$TESTDIR/dummyssh\"" ssh://user@dummy/nonexistent local
-  remote: abort: there is no Mercurial repository here (.hg not found)!
+  remote: abort: repository nonexistent not found!
   abort: no suitable response from remote hg!
   [255]
 
 non-existent absolute path
 
   $ hg clone -e "python \"$TESTDIR/dummyssh\"" ssh://user@dummy//`pwd`/nonexistent local
-  remote: abort: there is no Mercurial repository here (.hg not found)!
+  remote: abort: repository /$TESTTMP/nonexistent not found!
   abort: no suitable response from remote hg!
   [255]
 
@@ -128,7 +128,7 b' pull from wrong ssh URL'
 
   $ hg pull -e "python \"$TESTDIR/dummyssh\"" ssh://user@dummy/doesnotexist
   pulling from ssh://user@dummy/doesnotexist
-  remote: abort: there is no Mercurial repository here (.hg not found)!
+  remote: abort: repository doesnotexist not found!
   abort: no suitable response from remote hg!
   [255]
 

tests/test-ssh.t

@@ -34,14 +34,14 b' configure for serving'
 repo not found error
 
   $ hg clone -e "python \"$TESTDIR/dummyssh\"" ssh://user@dummy/nonexistent local
-  remote: abort: there is no Mercurial repository here (.hg not found)!
+  remote: abort: repository nonexistent not found!
   abort: no suitable response from remote hg!
   [255]
 
 non-existent absolute path
 
   $ hg clone -e "python \"$TESTDIR/dummyssh\"" ssh://user@dummy/`pwd`/nonexistent local
-  remote: abort: there is no Mercurial repository here (.hg not found)!
+  remote: abort: repository $TESTTMP/nonexistent not found!
   abort: no suitable response from remote hg!
   [255]
 
@@ -119,7 +119,7 b' pull from wrong ssh URL'
 
   $ hg pull -e "python \"$TESTDIR/dummyssh\"" ssh://user@dummy/doesnotexist
   pulling from ssh://user@dummy/doesnotexist
-  remote: abort: there is no Mercurial repository here (.hg not found)!
+  remote: abort: repository doesnotexist not found!
   abort: no suitable response from remote hg!
   [255]