errors: raise InputError from revpair() iff revset provided by the user

Same reasoning as for `revrange()` in an earlier patch.

Differential Revision: https://phab.mercurial-scm.org/D11561

hgext/extdiff.py

@@ -101,6 +101,7 b' from mercurial import ('
     error,
     filemerge,
     formatter,
+    logcmdutil,
     pycompat,
     registrar,
     scmutil,
@@ -568,7 +569,7 b' def dodiff(ui, repo, cmdline, pats, opts'
         ctx1b = repo[nullrev]
         ctx2 = scmutil.revsingle(repo, to_rev, None)
     else:
-        ctx1a, ctx2 = scmutil.revpair(repo, revs)
+        ctx1a, ctx2 = logcmdutil.revpair(repo, revs)
         if not revs:
             ctx1b = repo[None].p2()
         else:

mercurial/commands.py

@@ -2610,7 +2610,7 b' def diff(ui, repo, *pats, **opts):'
         ctx2 = scmutil.revsingle(repo, to_rev, None)
     else:
         repo = scmutil.unhidehashlikerevs(repo, revs, b'nowarn')
-        ctx1, ctx2 = scmutil.revpair(repo, revs)
+        ctx1, ctx2 = logcmdutil.revpair(repo, revs)
 
     if reverse:
         ctxleft = ctx2
@@ -6909,7 +6909,7 b' def status(ui, repo, *pats, **opts):'
         ctx1 = ctx2.p1()
     else:
         repo = scmutil.unhidehashlikerevs(repo, revs, b'nowarn')
-        ctx1, ctx2 = scmutil.revpair(repo, revs)
+        ctx1, ctx2 = logcmdutil.revpair(repo, revs)
 
     forcerelativevalue = None
     if ui.hasconfig(b'commands', b'status.relative'):

mercurial/logcmdutil.py

@@ -912,6 +912,18 b' def _makenofollowfilematcher(repo, pats,'
     return None
 
 
+def revpair(repo, revs):
+    """Resolves user-provided revset(s) into two revisions.
+
+    This just wraps the lower-level scmutil.revpair() in order to raise an
+    exception indicating user error.
+    """
+    try:
+        return scmutil.revpair(repo, revs)
+    except error.RepoLookupError as e:
+        raise error.InputError(e.args[0], hint=e.hint)
+
+
 def revrange(repo, specs, localalias=None):
     """Resolves user-provided revset(s).
 

tests/autodiff.py

@@ -4,6 +4,7 b' from __future__ import absolute_import'
 
 from mercurial import (
     error,
+    logcmdutil,
     patch,
     pycompat,
     registrar,
@@ -49,7 +50,7 b' def autodiff(ui, repo, *pats, **opts):'
     else:
         raise error.Abort(b'--git must be yes, no or auto')
 
-    ctx1, ctx2 = scmutil.revpair(repo, [])
+    ctx1, ctx2 = logcmdutil.revpair(repo, [])
     m = scmutil.match(ctx2, pats, opts)
     it = patch.diff(
         repo,