NIST's policy: sha-1 until 2010, after 2010 sha-2.

["J.C. Pizarro" <jcpiza@gmail.com>]

Dear Linus Torvalds,

What do you think to do when your git has to change from SHA-1 to SHA-2
  because of the weaker collision-resistance of SHA-1 in the next years?

    (e.g. from an damn developer trying to commit a collisioned-SHA-1 file)

http://csrc.nist.gov/groups/ST/hash/policy.html says

NIST's Policy on Hash Functions
-------------------------------
March 15, 2006: The SHA-2 family of hash functions (i.e., SHA-224,
SHA-256, SHA-384 and SHA-512) may be used by Federal agencies for all
applications using secure hash algorithms. Federal agencies should
stop using SHA-1 for digital signatures, digital time stamping and
other applications that require collision resistance as soon as
practical, and must use the SHA-2 family of hash functions for these
applications after 2010. After 2010, Federal agencies may use SHA-1
only for the following applications: hash-based message authentication
codes (HMACs); key derivation functions (KDFs); and random number
generators (RNGs). Regardless of use, NIST encourages application and
protocol designers to use the SHA-2 family of hash functions for all
new applications and protocols.