commands: improve help for -y/--noninteractive

Before, the help text said that Mercurial would assume 'yes' for all
prompts, but this is confusing since many prompts don't have any 'yes'
choice. It now more accurately describes what will happen.

mercurial/commands.py

@@ -31,7 +31,7 b' globalopts = ['
     ('', 'cwd', '',
      _('change working directory'), _('DIR')),
     ('y', 'noninteractive', None,
-     _('do not prompt, assume \'yes\' for any required answers')),
+     _('do not prompt, automatically pick the first choice for all prompts')),
     ('q', 'quiet', None, _('suppress output')),
     ('v', 'verbose', None, _('enable additional output')),
     ('', 'config', [],

tests/test-extension.t

@@ -185,7 +185,8 b" Check hgweb's load order:"
    -R --repository REPO    repository root directory or name of overlay bundle
                            file
       --cwd DIR            change working directory
-   -y --noninteractive     do not prompt, assume 'yes' for any required answers
+   -y --noninteractive     do not prompt, automatically pick the first choice
+                           for all prompts
    -q --quiet              suppress output
    -v --verbose            enable additional output
       --config CONFIG [+]  set/override config option (use 'section.name=value')
@@ -215,7 +216,8 b" Check hgweb's load order:"
    -R --repository REPO    repository root directory or name of overlay bundle
                            file
       --cwd DIR            change working directory
-   -y --noninteractive     do not prompt, assume 'yes' for any required answers
+   -y --noninteractive     do not prompt, automatically pick the first choice
+                           for all prompts
    -q --quiet              suppress output
    -v --verbose            enable additional output
       --config CONFIG [+]  set/override config option (use 'section.name=value')

tests/test-help.t

@@ -247,7 +247,8 b' Test short command list with verbose opt'
    -R --repository REPO    repository root directory or name of overlay bundle
                            file
       --cwd DIR            change working directory
-   -y --noninteractive     do not prompt, assume 'yes' for any required answers
+   -y --noninteractive     do not prompt, automatically pick the first choice
+                           for all prompts
    -q --quiet              suppress output
    -v --verbose            enable additional output
       --config CONFIG [+]  set/override config option (use 'section.name=value')
@@ -331,8 +332,8 b' Verbose help for add'
    -R --repository REPO      repository root directory or name of overlay bundle
                              file
       --cwd DIR              change working directory
-   -y --noninteractive       do not prompt, assume 'yes' for any required
-                             answers
+   -y --noninteractive       do not prompt, automatically pick the first choice
+                             for all prompts
    -q --quiet                suppress output
    -v --verbose              enable additional output
       --config CONFIG [+]    set/override config option (use