Better behavior for failed connections in `brew search`

Fixes #20868.
imagemagick: use same test file on 10.6/7/8.
mysql-connector-odbc: use MysqlDependency.
Remove message from default_formula'd requirements
versions: pass string to factory

Closes #20951.
mutt: Fix dev docs to use head without SHA1

Signed-off-by: Misty De Meo <mistydemeo@gmail.com>
mutt: Add confirm-attachment patch

Signed-off-by: Misty De Meo <mistydemeo@gmail.com>
mutt: Fix slang - should be s-lang

Closes #20893.

Signed-off-by: Misty De Meo <mistydemeo@gmail.com>
mutt: fix second 'slang' usage
Nginx --devel 1.5.2

Closes #20961.

Signed-off-by: Adam Vandenberg <flangy@gmail.com>
pigdin 2.10.7

This is the X11 chat client.

Note that this variously conflicts with finch (command-line client) and
libpurple (chat library), so will be sorted out later.

Closes #13901.