graft: use single quotes around command hint

Windows command lines use double quotes to quote arguments with spaces.
This change is in a series to unify around using single quotes around
commands, and double quotes around interior arguments.

tests/test-confused-revert.t

@@ -60,7 +60,7 b' Revert should fail:'
 
   $ hg revert
   abort: uncommitted merge with no revision specified
-  (use "hg update" or see "hg help revert")
+  (use 'hg update' or see 'hg help revert')
   [255]
 
 Revert should be ok now:

tests/test-graft.t

@@ -209,7 +209,7 b' Graft out of order, skipping a merge and'
   my e@1905859650ec+ other e@9c233e8e184d ancestor e@4c60f11aa304
   warning: conflicts while merging e! (edit, then use 'hg resolve --mark')
   abort: unresolved conflicts, can't continue
-  (use hg resolve and hg graft --continue --log)
+  (use 'hg resolve' and 'hg graft --continue --log')
   [255]
 
 Summary should mention graft:
@@ -246,7 +246,7 b' Graft again:'
   merging e
   warning: conflicts while merging e! (edit, then use 'hg resolve --mark')
   abort: unresolved conflicts, can't continue
-  (use hg resolve and hg graft --continue)
+  (use 'hg resolve' and 'hg graft --continue')
   [255]
 
 Continue without resolve should fail:
@@ -441,7 +441,7 b' Resolve conflicted graft'
   $ hg graft 1 --tool internal:fail
   grafting 1:5d205f8b35b6 "1"
   abort: unresolved conflicts, can't continue
-  (use hg resolve and hg graft --continue)
+  (use 'hg resolve' and 'hg graft --continue')
   [255]
   $ hg resolve --all
   merging a
@@ -481,7 +481,7 b' Resolve conflicted graft with rename'
   $ hg graft 2 --tool internal:fail
   grafting 2:5c095ad7e90f "2"
   abort: unresolved conflicts, can't continue
-  (use hg resolve and hg graft --continue)
+  (use 'hg resolve' and 'hg graft --continue')
   [255]
   $ hg resolve --all
   merging a and b to b
@@ -768,7 +768,7 b' graft --continue after --force'
   $ hg graft 28 --force --tool internal:fail
   grafting 28:50a516bb8b57 "28"
   abort: unresolved conflicts, can't continue
-  (use hg resolve and hg graft --continue)
+  (use 'hg resolve' and 'hg graft --continue')
   [255]
   $ hg resolve --all
   merging a

tests/test-issue1175.t

@@ -72,7 +72,7 b' http://bz.selenic.com/show_bug.cgi?id=44'
   merging b
   warning: conflicts while merging b! (edit, then use 'hg resolve --mark')
   abort: unresolved conflicts, can't continue
-  (use hg resolve and hg graft --continue)
+  (use 'hg resolve' and 'hg graft --continue')
   [255]
   $ echo a > b
   $ echo b3 >> b